Table Top Wet Grinder
- 1 What is a wet grinder used for?
- 2 Why is wet grinder better?
- 3 Is wet grinder better than mixer?
- 4 Which mill is preferred for wet grinding?
- 5 Can coffee grinder be used for wet grinding?
What is a table top wet grinder?
Buy Wet Grinders Online – For an Indian household, a wet grinder is one of the most useful appliances. This appliance is used to grind soaked grains, shred coconut pieces, mash vegetables and much more. This grinder minimises your effort in making the batter for dosas, vadas and idlis.
What is a wet grinder used for?
5. What kind of food is best for wet grinding? – South Indian cuisine relies heavily on wet grinders for making favorite meals like dosa, idly, vada, appam, and paniyaram. Wet grinders are used to produce pastes from grains and lentils and are utilized extensively in making these foods.
What is wet grinding called?
Wet Grinding, also known as wet milling, is a process of taking materials in a liquid form or slurry and reducing particles, such as agglomerates, by breaking them apart or shearing them down in size.
What is the difference between a table top grinder and a wet grinder?
Wet Grinder Vs Mixer Grinder: Functionality – A mixer grinder can be used for making idli dosa batter, grinding masala, making spice powders, milkshakes, smoothies, juices etc. Modern mixer grinders come with food processor attachments too which can be used for slicing, chopping, grating, kneading and citrus juicing.
Why is wet grinder better?
Types of wet grinders – Originally stones manually operated, modern wet grinders are available for both home usage and larger-scale commercial production. A wet grinder consists of granite stones rotating inside a metal drum with the help of an electric motor, Dosa is made from a batter obtained by wet-grinding rice and pulses.
Is it worth it to buy a wet grinder?
Answer Every household needs a wet grinder if they prepare dosas, idlis, or other South Indian foods regularly. This grinder is more valuable than a standard mixer since it is designed for quick and efficient grinding. It can grind items into a lovely batter.
Is it necessary to use a wet grinder?
Wet grinders are a must-have appliance in any Indian kitchen that regularly prepares dosas, idlis, chutneys, or cheelas. Wet grinder machines are a must-have kitchen tool if you want to save time while enjoying well-prepared, silky batters. A wet grinder is also necessary if you enjoy making pastes and chutneys.
This machine is intended to grind foods such as coconut and grains. It’s also great for making vadas, idlis, and dosas. Furthermore, standard wet grinders are commonly used by professionals and large families. These are quite large and heavy on the other hand table top wet grinders are convenient and widely used in nuclear families because they take up less counter space.
Also, tilted wet grinders function similarly to tabletop wet grinders but with the addition of a mechanism for tilting the jar and emptying its contents. If you want to find the best wet grinder for your home, you should surely go for one of the below-mentioned products which have been selected considering their affordability and reliability.
Is wet grinder better than mixer?
3. Power Consumption – A wet grinder is much more efficient than a mixer grinder. It takes more time to grind the ingredients finely. However, the motor works faster and consumes more energy. On the other hand, the mixer grinder has an advanced setting system that d oesn’t need much time to grind food ingredients. Hence, it consumes very little energy than a wet grinder.
What is the alternative to a wet grinder?
Convenience: Mixer grinders are more convenient to use than wet grinders. They are smaller, lighter, and easier to handle, and can be stored easily in a kitchen. On the other hand, wet grinders are larger and heavier, and can be difficult to move and store.
What are the top 3 uses of a grinder?
Angle grinders typically have three basic functions; cutting, grinding and polishing. In terms of cutting they run at a high speed and facilitate cutting tasks with ease as well as giving better precision in terms of grinding than stationary grinders as they are handheld.
Can we grind dry spices in wet grinder?
Can we grind masala in wet grinder? Yes, wet grinders are also widely used to grind chutneys and masala on large scale besides metals, coconuts and food grains.
Can you wet grind concrete?
“Which one’s better; wet or dry concrete grinding?” This question is often asked by people looking to upgrade their flooring. The truth is that it depends on a lot of factors, circumstances, and, to an extent, personal preferences. Here at Concrete Grinding Concepts, we use a balance of both methods depending on each case.
Let’s find out more. Wet Concrete Grinding If you think it’s called “wet concrete grinding” because water is involved somehow, you’re absolutely right. Wet concrete grinding and polishing were developed long before the dry grinding method; so, it’s natural for contractors to opt for this method – particularly in areas with an abundance of water supply.
Pros of Wet Concrete Grinding The main role of water here is to cool down the diamond tooling and also provide lubrication to reduce friction. Without this lubrication, there is an increased risk of excessive heat generation (from the friction), which will melt the epoxy resin and glaze over the tooling.
You don’t want that. So, in a way, wet concrete grinding extends the life of your tooling. Additionally, a great deal of concrete grinding contractors prefer this method not just because of familiarity but also because water reduces the dust particles inhaled by the operator. Dust particles containing Silica can be quite toxic, putting the person at more risk of developing silicosis – a condition that leaves scar tissue in the lungs.
As great as it is, wet concrete grinding also has its setbacks. Let’s delve into a few. Cons of Wet Concrete Grinding It uses a lot of water, thus causing wastage and aggravating the global water crisis. Unless it is entirely necessary dry concrete grinding is much better for the environment than wet concrete grinding.
- Wet grinding leaves slurry – a mixture of cooling water and concrete fines.
- It takes a lot of time to clean the slurry, and safely disposing of it without negatively impacting the environment is a significant challenge.
- Wet grinding just doesn’t give you that smooth, shiny appearance that dry grinding does.
If you’re going for a decorative concrete finish, wet grinding may not be the most ideal. Dry Concrete Grinding Technological progress has resolved one of the greatest setbacks of dry concrete grinding; dust exposure. Newer models come already fitted with dust extraction systems and filters to minimize dust exposure to the operator and the environment.
This method simultaneously grinds and cleans the area and, in the process leaving behind a surface that’s ready to be polished. Pros of Dry Concrete Grinding It is more environment-friendly since it filters and collects dust particles and does not leave slurry. Speaking of slurry, the lack of it in this method means that you get to save much time in the clean-up process.
It gives a far better shine and finishes compared to wet concrete grinding. Cons of Dry Concrete Grinding It may not be the most ideal when dealing with very hard concrete. In such a case, you are advised to start with the wet grinding method and then switch to a dry grinding method afterward.
The dust extraction system makes the equipment a little more expensive. Parting Shot Ultimately, the choice between these two methods will largely be driven by personal preferences, budget, time necessity. Bad flooring can ruin the appearance of the entire room – regardless of how much effort was put into it.
Do not risk having your floors done by inexperienced people. If you’re in need of such services in Melbourne, Australia, you can count on the experienced professional team at Concrete Grinding Concepts. Check out our website www.concretegrindingconcepts.com.au to learn more about our services.
Which mill is preferred for wet grinding?
Grinding Mills and Their Types –
satyendra April 9, 2015 0 Comments autogenous grinding, ball mill, grinding mills, hammer mill, rod mill, roller mill, SAG,
Grinding Mills and Their Types In various fields of the process industry, reduction of size of different materials is a basic unit operation. The basic idea is to reduce particle sizes of material under handling by cutting or breaking those to smaller pieces.
The usual reason for size reduction is normally the need for smaller size, but it can also be desired shape, size or number of particles. The functions of mechanics in machines made for size reduction are usually based on the principles namely (i) compression, (ii) impact, (iii) attrition, and (iv) shear.
(Refer article under link http://www.ispatguru.com/crushers-and-their-types/ ) Grinding mills are size reductions machines that often follow crushers in the processes where finer products are desired after crushing. Different grinding machines are usually named as mills, for example rod mills, ball mills, and attrition mills.
Because of the name, verb milling is also been used as a synonym for grinding. Milling, sometimes also known as fine grinding, pulverizing or comminution, is the process of reducing materials to a powder of fine or very fine size. It is distinct from crushing or granulation, which involves size reduction of a material to a smaller size.
Milling is used to produce a variety of materials which either have end uses themselves or are raw materials or additives used in the manufacture of other products. A wide range of mills has been developed each for particular applications. Some types of mills can be used to grind a large variety of materials whereas others are used for certain specific grinding requirements.
- Material grinding is quite often an integral part of an industrial process, whether carried out on a large or small scale and in some cases the grinding mill may be the single most costly item for in the process of operation.
- Installing a grinding mill which is suitable for the purpose, is one of the main requirements for cost effective and trouble free processing of materials, if a grinding stage is involved.
Most types of readily available hammer mills for agricultural grinding are not suitable for grinding of minerals. Material characteristics The characteristics of the material, which are to be taken into account during the selection of the grinding mill, are (i) hardness, (ii) brittleness, (iii) toughness, (iv) abrasiveness, (v) stickiness, (vi) softening and melting temperature, (vii) structure (e.g.
close grained or cellular), (viii) specific gravity, (ix) free moisture content, (x) chemical stability, (xi) homogeneity, and (xii) purity. The hardness of a material is probably the most important characteristic to be considered when deciding on what type of mill to choose. Trying to grind a material which is too hard results either in costly damage to the mill or an expensive maintenance requirement.
Generally for harder materials, specialized and expensive type of grinding mills are used. In addition if a particular mill can be used over a range of hardness scales, the harder the material the lower the throughput for a given size requirement. Another characteristic of a material that is to be known is the brittleness, which is the degree to which a material breaks easily.
Most minerals are brittle, as opposed to metals which are ductile, although some to a greater degree than others. Brittleness does not equate with hardness as brittle materials can be hard or may not be hard. It is not easy to grind materials which are not brittle to some degree. In case of dry milling, free moisture content of the material is to be as low as possible.
In practice, this can be a problem, especially in humid regions where the moisture can cause the material to stick to the grinding media. Different mills behave in different ways with moist materials and in some cases drying of the raw materials may be required.
The final size of the material after grinding is important. Usually required degree of fineness is specified which is normally stipulated that a proportion of the material is finer than a particular size. Usually this is 90 % or 95 % but may be 99 % for particularly demanding application. The grinding mills are categorized in three groups, namely (i) tumbling mills,(ii) roller mills, and (iii) very fine grinding mills which include (a) high speed pulverizing or hammer mill, (b) vibrating mill, (c) pin mill, (d) turbo mill, (e) fluid energy mill, (f) stirred media mill.
Terms used in grinding of materials
Milling circuit – It can be either open or closed. The milling circuit is the complete mill system from beginning to end, which includes feed mechanism, mill, classifier, separator, product collector, etc. In a closed mill circuit, the oversize particles are returned from the post milling processes to be regrinding, while in an open circuit the process there is no feedback loop.Air classification – It is also known as pneumatic classification. It is sizing of particles using a mechanical air separator.Batch mills – These mills receive a discrete quantity of charge material which is ground and then discharged. The process is then repeated.Continuous mills – These mills accept a continuous flow of feedstock and hence can operate on a continuous basis. Both batch and continuous mills have their relative merits and demerits.Peripheral and trunnion discharge – For cylindrical mills which are continuously fed, the discharge of the ground product can be either through the periphery of the mill (peripheral discharge) or through the far end of the mill (trunnion discharge).
Tumbling mills Tumbling autogenous (AG) mills are drum mills which consist of horizontally rotating slightly inclined cylinders of large diameter and small length and fitted with lifting bars. Coarse feed is entering the mill from one end and outlet is at the other end.
- In the mill, the feedstock is lifted and then allowed to drop through a significant height.
- Three significant mechanisms cause the breakdown of the mineral.
- These are (i) impact due to the fall of the mineral onto the charge below causes a reduction in the size of the feedstock, (ii) attrition of smaller particles between larger grinding bodies.
and (iii) abrasion or rubbing off of particles from the larger bodies. Steel or ceramic balls are often added to aid with the reduction process. In this case the mill is then referred to as a semi autogenous (SAG) mill. The process can be carried out wet or dry.
Feed is grinded during its way through the mill. The mill is normally used for grinding of ores. Lining of the cylinder plays very important role. It protects the mill from abrasions and at the same time it helps in lifting of the material from the bottom of cylinder. The types of lining are (i) smooth liner, (ii) wave liner, (iii) ship lap liner, (iv) step liner, and (v) Osborn liner.
Removal of the final product can be carried out using air (where the process is dry) removing only the fines. Rotational speed is usually fairly low, about 80 % of critical speed (critical speed is the speed at which the charge will be pinned to the rotating drum and does not drop) and typical drum diameter ranges from 2 to 10 meters.
- This type of mill is often used as a single stage process, providing sufficient size reduction in a single process.
- Alternatively, it can be part of a two stage process where further size reduction is required.
- This type of mill is only suited for those kind of ores which are of a fairly coarse nature, but once they are broken, they readily disintegrate into smaller sizes.
Typically, this type of mill can produce a product with a fineness of less than 0.1 mm. Testing of materials is needed beforehand for determining the suitability of the ore for processing in an autogenous mill. This type of mill has a distinct advantage of accepting coarse input material and supplying a relatively fine ground product.
This advantage can provide a reduction in the plant cost, since a single mill can be used as a substitute for two or more stages. There is little wear as the grinding is often carried out by the material itself. Autogenous mills are more suited to large installations i.e. more than 50 tons per hour and have a power requirement ranging from 40 kW up to hundreds of kW.
Rod mills This type of mill is only suited for those kinds of ores which are of a fairly coarse nature but once they are broken, disintegrate readily into small size. Typically this type of mill can deliver a product with a fineness of less than 0.1 mm.
- Testing of material is needed before hand to determine the suitability of the ore for processing in an autogenous mill.
- The rod mill (Fig 1) is a tumbling mill which is having a large percentage of its volume (30 % to 40 %) loaded with steel rods.
- The rods are placed axially in the mill and are loose and free to move within the mill.
The internal lining of the drum has a series of lifters which raise the rods and drop them at a predetermined point. The liners prevent long and heavy rods to slide on the cylinder lining and help them to lift up. Because of the high kinetic energy of a dropping rod, it is important to pay attention to protecting the cylinder when choosing a liner for the mill.
The material is fed in at one end with a maximum size of about 25 mm. The rods crush the material and as the charge passes through the mill, it is reduced in size to approximately 2 mm to 0.1 mm. The mill can be fed from one end with the product removed from the other end or, alternatively, the mill can be fed from both ends with the discharge at the centre.
The process can be wet or dry but generally it is carried out wet. Maximum rod length is about 6 to 7 meters, otherwise there is a risk of the rods bowing. The drum diameter is limited to 0.6 or 0.7 times the length of the mill. Rod mills are used for grinding hard minerals. Fig 1 Cross sections of a rod mill and a bar mill Ball mills Ball mill (Fig 1) is same kind of mill as rod mill, except that it is filled with balls instead of rods. Because of balls have greater ratio of surface area than rods they are more suitable for fine grinding.
Balls are also lighter, so the kinetic energy of a single dropping ball is smaller than a rod. The lining material is of great importance as there is a significant amount of wear taking place due to the action of the steel balls. The mill consists of a cylindrical drum, sometimes tapered at one end, and usually has a charge of steel balls (up to 40 % by volume) ranging in size up to 125 mm for larger mills.
Product size can be as small as 0.005 mm, but product size is dependent upon the time the charge spends in the grinding zone and therefore the reduction rate is a function of the throughput. The speed of rotation is optimum at about 75 % of critical speed.
- Some mills are compartmentalized with each subsequent section having a smaller ball size.
- The material can pass through to the proceeding section, but the balls cannot.
- This ensures that the smaller particles are attacked by the smaller grinding media.
- Ball mill is a versatile grinding mill and has a wide range of applications.
The mill can vary in size from small batch mills up to mills with outputs of hundreds of tons per hour. They are the most widely used of all mills. Roller mills Roller mills are basically of two distinct types. The first has a series of rollers which rotate around a central axis within a drum.
- The reduction takes place between the rollers and the drum.
- The second type is where there are a series of fixed rollers and a rotating table.
- The milling takes place between the rollers and the table.
- This type of mill is used for dry grinding only and accepts only relatively soft materials.
- Small machines can have a throughput of only a few tens of kg per hour whereas larger machines are capable of handling up to 40 or 50 tons per hour and occasionally more.
Feed size varies according to the machine. The machines are often fitted with screens for closed circuit grinding. Product size can be controlled by changing screens. Very fine grinding mills The following are the mills used for very fine grinding. Hammer mills Hammer mills are high speed mills operating at speeds of between 2000 rpm and 6000 rpm.
- A set of ‘hammers’ rotate about a central axis in a vertical or horizontal plane.
- The hammers are either be fixed or are swinging freely.
- The whole system is enclosed in a cylindrical casing.
- Feed is dropped to mill from the top of the casing and the outlet for the product is usually via a screen which sieves the product and allows only the required size of particle to pass.
The product size can be extremely fine, although an air classifier is required when such product size is required. Maximum capacity is of the order of 10 tons per hour and power consumption is relatively high. Rotating hammer mills are suited for the milling of softer materials.
- Pin, air classifying and turbo mills A pin mill comprises two discs, one rotating and one stationary which are fitted with intermeshing pins set in a concentric pattern.
- The charge is fed into the centre of the discs and is broken down as it moves outwards through the pins which are moving at very high speed (up to 20,000 rpm).
The air classifying mill is similar in construction to the pin mill but incorporates a built in classifier. This type of mill produces a significant airflow through the machine to aid with keeping temperature as low as possible. Oversize materials, which pass through the mill, are usually recycled.
Turbo mills use a similar concept but the rotating disc is fitted with paddles or bars rather than pins. This rotating disc sits within a cage which is fitted with grids, screens or breaker plates. The mill is configured in such a way as to produce the desired particle size. Pin mills are capable of very fine grinding without the need for screens and provide a uniform product size.
Air classifying mills are used where the product is temperature sensitive. They are suitable for relatively soft materials and for small quantities of material. Wear on the pins is significant if used continuously. Vibratory mills Vibratory mill does not rely on rotation for the main grinding action.
The vibrating mill has a grinding chamber which is filled to around 65 % to 80 % of its capacity with grinding media such as balls or rods. The chamber is vibrated at a frequency of between 1000 and 1500 times per minute (can be variable speed) by cams or unbalanced weights. The grinding action is efficient and thorough.
Grinding media material and chamber lining can vary depending on application. Vibrating mills are usually batch mills and can grind hard or soft materials. Maximum throughput is about 20 tons per hour. The feed size is normally kept fairly small. Although final product size can be as low as 0.005 mm, this type of mill is often used for less fine applications.
Product size and shape is a function of the time spent in the mill, media type and size, and frequency of vibration. Stirred media mills Stirred media mills are usually constructed in the form of a cylindrical drum inside which there are a series of rods, arms or perforated discs which are rotated on a central shaft.
The drum is loaded with grinding media, such as metal balls or glass sand. The media and the charge is ‘stirred’ together and thus the grinding takes place. These mills are suited primarily for very fine grinding of soft materials. They are normally used with wet grinding but can also be used for dry grinding.
- Product size is as small as 0.005 mm.
- Fluid energy mills The general principle of operation in a fluid energy mill is that the material to be ground is fed into a grinding chamber in a high speed, high pressure and, often, high temperature jet of air (or other gas).
- The particles collide violently and this causes comminution to take place.
Various designs of fluid energy mill exist, the most common being the micronizer. This mill has a shallow circular grinding chamber and a series of peripheral jets set tangentially to a common circle. The turbulence causes bombardment which effects a rapid reduction in particle size.
- A centrifugal classification system keeps larger particles within the chamber while allowing fine particles to leave.
- In a well designed fluid energy mill, there is usually almost no contact between the charge and the mill lining.
- These mills are suitable for hard or soft materials to be reduced to 0.02 mm or less.
This method of milling tends to be energy intensive and slow but is suitable where the product is highly sensitive to heat or contamination from grinding media. Attrition mills Attrition mills are the most common type of mill and are the traditional mills for grain milling in many regions of the world.
They are based on attrition grinding between two circular stones, one rotating and the other stationary. Plate mills use a similar principle but are constructed of steel or ceramic plates and used more commonly in the vertical plane. Output from such a mill is low and the mill in used only for small scale milling.
High pressure grinding rolls The high pressure grinding rolls, often referred to as HPGRs or roller press, consists out of two rollers with the same dimensions, which are rotating against each other with the same circumferential speed. The special feeding of bulk material through a hopper leads to a material bed between the two rollers.
The bearing units of one roller can move linearly and are pressed against the material bed by springs or hydraulic cylinders. The pressures in the material bed are greater than 50 MPa. In general, they achieve 100 to 300 MPa. By this the material bed is compacted to a solid volume portion of more than 80 %.
The roller press has a certain similarity to roller crushers and roller presses for the compacting of powders, but purpose, construction and operation mode are different. Extreme pressure causes the particles inside of the compacted material bed to fracture into finer particles and also causes micro fracturing at the grain size level.
Material properties – The choice of mill type is primarily dependent upon the properties of the material which is to be ground by it. It is vitally important to match the mill and material characteristics properly.Capacity – The scale of the operation determines the size of the mill which is required. Throughput or capacity is often given in tons per hour ( kg per hour for small mills).Reduction ratio and final size requirement. -This parameter decides whether a single mill is sufficient for final product requirements or if a multi stage grinding plant is be needed. Normally greater the reduction ratio, the larger is the likelihood for a multi stage process.Power requirements and type of power supply – Access to a power supply of suitable capacity is essential. The power requirement for a grinding mill is normally given in the mill specification document. Specific power consumption ( kWh per ton) is good comparative guide.Wet or dry product – Products which can be accepted in a wet state, such as slurries, can be milled wet which save power and reduce dust related problems. As a general rule, only tumbling mills are used for wet grinding, although other mills can be used for wet grinding in certain circumstances.Continuous or batch operation – Some mills can be designed in such a way as to enable continuous milling. This is important where the throughput is high, as well as making loading and emptying easier within the process. Some mills will only accept batch loads.Portable or stationary equipment required – Depending on the nature of the operation, the equipment can be installed permanently or can be portable. Portable equipment is useful for operations which move frequently to the dispersed sites.Classification – When considering a mill for a particular application, one needs to consider the classification mechanism that is needed for the process.Cost – Obviously cost is an important factor. It is important to consider all the costs which include (i) capital costs of the mill, (ii) capital costs of peripherals, (iii) transport costs, (iv) operating costs, and (v) maintenance costs
Which blade is used for wet grinding?
Wet Grinding Blade – The wet grinding blade usually comes with four arms with sharp edges. These blades are usually found in the larger jars having a capacity of 1L or more. They are helpful for wet grinding purposes, such as preparing batter for idly, dosas, vadas, etc. It is better to ensure that you use a sufficient quantity of water when using these blades to get the desired consistency.
What are the 4 different types of surface grinders?
Cutting Tool Applications, Chapter 17: Grinding Methods and Machines Grinding, or abrasive machining, once performed on conventional milling machines, lathes and shapers, are now performed on various types of grinding machines. Grinding machines have advanced in design, construction, rigidity and application far more in the last decade than any other standard machine tool in the manufacturing industry.
Grinding machines fall into five categories: surface grinders, cylindrical grinders, centerless grinders, internal grinders and specials. Surface grinding Surface grinders are used to produce flat, angular and irregular surfaces. In the surface grinding process, the grinding wheel revolves on a spindle; and the workpiece, mounted on either a reciprocating or a rotary table, is brought into contact with the grinding wheel.
Four types of surface grinders are commonly used in industry: the horizontal spindle/reciprocating table; the horizontal spindle/rotary table; the vertical spindle/reciprocating table; and the vertical spindle/rotary table. Horizontal spindle/reciprocating table.
This surface grinder is the most commonly used type in machining operations. It is available in various sizes to accommodate large or small workpieces. With this type of surface grinder, the work moves back and forth under the grinding wheel. The grinding wheel is mounted on a horizontal spindle and cuts on its periphery as it contacts the workpiece.
Horizontal spindle/rotary table. This surface grinder also has a horizontally mounted grinding wheel that cuts on its periphery. The workpiece rotates 360 degrees on a rotary table underneath the wheelhead. The wheelhead moves across the workpiece to provide the necessary cross feed movements.
- Vertical spindle/reciprocating table.
- This type is particularly suited for grinding long and narrow castings, like the bedways of an engine lathe.
- It removes metal with the face of the grinder wheel while the work reciprocates under the wheel.
- The wheelhead assembly, as on most other types of surface grinders, moves vertically to control the depth of cut.
The table moving laterally accomplishes cross feed. Vertical spindle/rotary table. This grinding machine is capable of heavy cuts and high metal-removal rates. Vertical spindle machines use cup, cylinder, or segmented wheels. Many are equipped with multiple spindles to successively rough, semi-finish, and finish large castings, forgings, and welded fabrications.
- Workholding devices.
- Almost any workholding device used on a milling machine or drill press can be used on surface grinders.
- However, the most common workholding device on surface grinders is a magnetic chuck.
- Cylindrical grinding Cylindrical grinding is the process of grinding the outside surfaces of a cylinder.
These surfaces may be straight, tapered or contoured. Cylindrical grinding operations resemble lathe-turning operations. They replace the lathe when the workpiece is hardened or when extreme accuracy and superior finish are required. As the workpiece revolves, the grinding wheel, rotating much faster in the opposite direction, is brought into contact with the part.
- The workpiece and table reciprocate while in contact with the grinding wheel to remove material.
- Workholding devices.
- Workholding devices and accessories used on center-type cylindrical grinders are similar to those used on engine lathes.
- Independent, universal and collet chucks can be used on cylindrical grinders when the work is odd-shaped or contains no center hole.
These also are used for internal grinding operations. Centerless grinding Centerless grinding machines eliminate the need to have center holes for the work or to use workholding devices. In centerless grinding, the workpiece rests on a workrest blade and is backed up by a second wheel, called the regulating wheel.
The rotation of the grinding wheel pushes the workpiece down on the workrest blade and against the regulating wheel. The regulating wheel, usually made of a rubber-bonded abrasive, rotates in the same direction as the grinding wheel and controls the longitudinal feed of the work when set at a slight angle.
By changing this angle and the speed of the wheel, the workpiece feed rate can be changed. Intemal grinding Internal grinders are used to finish straight, tapered or formed holes accurately. The most popular internal grinder is similar in operation to a boring operation in a lathe: The workpiece is held by a workholding device, usually a chuck or collet, and revolved by a motorized headstock.
- A separate motor head in the same direction as the workpiece revolves the grinding wheel.
- It can be fed in and out of the work and also adjusted for depth of cut.
- Special grinding processes Special types of grinders are grinding machines made for specific types of work and operations, for example: Tool and cutter grinders.
These grinding machines are designed to sharpen milling cutters, reamers, taps and other machine tool cutters. The general-purpose cutter grinder is the most popular and versatile tool-grinding machine. Various attachments are available for sharpening most types of cutting tools.
- Jig grinding machines.
- Jig grinders were developed to locate and accurately grind tapered or straight holes.
- Jig grinders are equipped with a high-speed vertical spindle for holding and driving the grinding wheel.
- They utilize the same precision locating system as do jig borers.
- Thread grinding machines.
These are special grinders that resemble the cylindrical grinder. They must have a precision lead screw to produce the correct pitch, or lead, on a threaded part. Thread grinding machines also have a means of dressing or truing the cutting periphery of the grinding wheel so that it will produce a precise thread form on the part.
Creep-feed grinding Traditionally, grinding has been associated with small rates of metal removal and fine finishing operations. However, grinding also can be used for large-scale metal-removal operations, similar to milling, broaching, and planning. In creep-feed grinding, developed in the late 1950s, the wheel depth of cut is as much as 0.25 in.
and the workpiece speed is low. Its overall competitive position with other material-removal processes indicates that creep-feed grinding can be economical for specific applications, such as in grinding shaped punches, twist-drill flutes, and various complex super alloy parts.
The wheel is dressed to the shape of the workpiece to be produced. Although generally one pass is sufficient, a second pass may be necessary for improved surface finish. Grinding wheel wear The wear of a grinding wheel may be caused by three actions: attrition or wearing down, shattering of the grains, or breaking of the bond.
In most grinding processes, all three mechanisms are active to some extent. Attritions wear is not desirable because the dulled grains reduce the efficiency of the process, resulting in increased power consumption, higher surface temperatures, and surface damage.
However, attrition must go on to some extent, with the forces on the grit being increased until they are high enough to shatter the grit or break the bond posts holding the dulled grit. The action of particles breaking away from the grains serves to keep the wheel sharp without excessive wear. However, the grains must eventually break from the bond or the wheel will have to be dressed.
Rupturing the bond post that holds the grit allows dull grains to be sloughed off, exposing new sharp edges. If this occurs too readily, the wheel diameter wears down too fast. This raises wheel costs and prohibits close sizing on consecutive parts. G-ratio.
- The G-ratio is the ratio of the amount of stock removed versus the amount of wear on the wheel, measured in cubic inches per minute.
- This ratio will vary from 1.0 to 5.0 in very rough grinding, and up to 25.0 to 50.0 in finish grinding.
- Even though grinding wheels are fairly expensive a high G-ratio is not necessarily economical, as this may mean a slower rate of stock removal.
It often takes some experimenting to find the wheel-metal combination, which is most economical for a job. Attritions wear. Attritions wear is responsible for the so-called “glazed” wheel that occurs when flat areas are worn on the abrasive grains but the forces are not high enough to break the dull grains out of the wheel face.
- Attritions wear of the wheel occurs most often when fine cuts are taken on hard abrasive materials.
- Taking heavier cuts or using a softer wheel that will allow the grains to break out can often avoid it.
- Grain fracture.
- The forces that cause the grain to shatter may arise from the cutting forces acting on the wheel, thermal conditions, shock loading, welding action between the grit and the chip, or combinations of these factors.
In finish grinding, this type of wheel wear is desirable, because it keeps sharp edges exposed, and still results in a low rate of wheel wear. In time, the wheel may become ‘loaded’ and noisy, and require dressing. A loaded wheel should be dressed by taking a few deep cuts with the diamond so that the metal-charged layer is removed, and the chips are not just pushed further into the wheel.
- Then, it should be finish-dressed according to the application requirements.
- Bond fracture.
- It is desirable to have worn grit break out of the wheel so that new cutting edges will be exposed.
- This breaking down of the bond should progress fast enough so that heat generation is sufficiently low to avoid surface damage.
On the other hand, bond breakdown should be slow enough so that wheel costs are not prohibitive. Normally, this means choosing the proper wheel grade for the job. Certain bond hardness is required to hold the grain in place. Softer wheels crumble too fast, while harder wheels hold the dull grit too long.
- Coated abrasives Typical examples of coated abrasives are sandpaper and emery cloth.
- The grains used in coated abrasives are more pointed than those used for grinding wheels.
- The grains are electrostatically deposited on flexible backing material, such as paper or cloth.
- The matrix or coating is made of resin.
Coated abrasives are available as sheets, belts and disks and usually have a much more open structure than the abrasives on grinding wheels. Coated abrasives are used extensively in finishing flat or curved surfaces of metallic or nonmetallic parts, and in woodworking.
The surface finishes obtained depend primarily on the grain sizes. Abrasive belt machining. Coated abrasives are also used as belts for high-rate material removal. Belt grinding has become an important production process, in some cases replacing conventional grinding operations such as the grinding of camshafts.
Belt speeds are usually in the range of 2,500 to 6,000 ft/min. Machines for abrasive-belt operations require proper belt support and rigid construction to minimize vibration. Grindability Grindability, in a like manner as machinability, may be thought of as the ease with which material can be removed from the workpiece by the action of the grinding wheel.
Surface finish, power consumption, and tool (wheel) life can be considered as fundamental criteria of the grindability of metals. In addition, there are the important factors of chip formation and susceptibility to damaging the workpiece. Chip formation, which leads to a ‘loaded’ wheel, is detrimental.
The most important machine setting affecting machinability, the cutting speed, is not as important an influence on grindability because grinding is done at more or less constant speed. Instead, the important factor becomes the nature of the grinding wheel.
- The type of grit, grit size, bond material, hardness and structure of the wheel all influence the grindability of the workpiece.
- The problems of tool material and configuration variables were discussed in connection with machinability.
- In grinding operations like snagging and cut-off work, the surface finish, and even the metallurgical damage the workpiece, may become relatively unimportant.
Wheel life and the rate of cut obtainable then become the criteria of grindability. The best way to determine grindability is to start with the selection of the proper wheel. Beginning with the manufacturer’s recommended grade for the conditions of the job and then trying wheels on each side of this grade will do this.
- Any improvement or deterioration in the grinding action, as evidenced by wheel wear, surface finish, or damage to the workpiece, can be noted.
- After the proper wheel has been chosen, wheel life data may be obtained.
- Usually, this can be done during the production run.
- Some of the factors to consider in establishing grindability ratings are discussed in the following examples relative to the performance metals.
Cemented carbide material cannot be ground with aluminum-oxide grit wheels. Although it can be ground with pure silicon-carbide wheels, the grinding ratio is very low and the material is easily damaged. Carbide is easily ground with diamond wheels if light cuts are taken to prevent damage to the workpiece material.
- However, diamond-grit wheels are quite expensive, and the overall grindability of this material is very low.
- High-speed steel can be ground quite successfully with aluminum-oxide grit wheels.
- The grinding ratio is low, the relative power consumption is high, and the possibility of damage to the workpiece is always present.
Overall grindability is quite low. Hardened steel (medium hard alloy or plain carbon steels) is easily ground with aluminum-oxide wheels. The grinding ratio is good, and damage to the workpiece is not a serious problem. The grindability rating is good. Soft steels (annealed plain carbon steels) grind with relatively low power consumption.
- Aluminum-oxide wheels are satisfactory, and the grinding ratio is quite high, but surface damage may be encountered.
- As a group, these materials are rated as having good grindability.
- Aluminum alloys (soft) grind with quite low power consumption, but they tend to load the wheel quickly.
- Wheels with a very oven structure are needed.
Grinding ratios are good. Silicon-carbide grit works well, and belt grinding outperforms wheel grinding in many cases. George Schneider, Jr., is the author of Cutting Tool Applications, a handbook to machine tool materials, principles, and designs. He is the Professor Emeritus of Engineering Technology at Lawrence Technological University, and former Chairman of the Detroit Chapter of the Society of Manufacturing Engineers.
Can coffee grinder be used for wet grinding?
Is there anything I should not try to grind in my coffee grinder? – Burr coffee grinders should only be used for coffee beans. Blade coffee or spice grinders give you more versatility to blend different ingredients in small quantities. However, you should avoid grinding any hard, wet or oily ingredients with your coffee grinder.
What is the problem with the wet grinder?
Basic Problems of A Mixer Grinder:- –
One of the most common problems in a mixer grinder is leaking from the jar. This happens mostly because your mixer grinder is very old and it is time for you to get the best mixer grinder in Kolkata. Other reasons this happens are due to loose blades, a crack in one of the jars, wearing out of a rubber gasket, etc. The finest mixer grinders can also work smoothly for over ten years. In case of a loose blade, you can just tighten them with a few tools. It could also be a fault in the gunmetal as they have a lifespan of three years. In that case, you need to call an expert and change it. But, if the container is broken, then get a new set. With time the sharpness of the blades disappear. As a result, things do not grind or mix well. But how do you identify the problem? Well, the first sign is when you notice your ingredients are coarse even after repetitively grinding it in the, The first tip you can try is fixing the blades with rock salt. All you have to do is pour a spoon of rock salt in the grinder and then switch it on. You can also replace the blades if this doesn’t work. Well, you can fix the blades yourself too. The process is very simple and you can look it up online or in the manual. When you constantly grind food items for a long period or use the mixer to grind food that is still very hot, it can start tripping. Therefore, it is best to grind food for too long or avoid pouring hot items in the mixer. Bring them to room temperature and then use it. The way to fix this is to switch off the mixer, unplug it, and reset it. The base of the blender which connects it to the jar is a coupler. They stop working when they get too old. It can also damage the coupler if you use it to blend frozen items, ice, etc at high speed. You cannot repair a coupler and the only option is to replace it.
These are the most common problems you face with a mixer grinder. If you want to get the best electrical appliances online, visit the website of, : What are the Most Common Mixer Grinder Problems and How to Fix Them?
Can I use blender instead of wet grinder?
A full-sized blender can easily replace a mixer grinder because it can do everything that a mixer grinder can do. Personal sized blenders, on the other hand, are much smaller in size. As a result, you may be unable to grind idli and dosa batter, churn butter, or blend anything in large quantities.
What do I need to know before buying a grinder?
List of Mixer Grinders Price, Specifications and Key Features –
|Parameters||750W mixer grinder||500W mixer grinder (maroon black)||500W mixer grinder (blue n white)||500W mixer grinder (White lid)||500W Mixer grinder 2 Jar||Fruice 400W Blender Grinder|
|Item Name||Mixer Grinder||Mixer Grinder||Mixer Grinder||Mixer Grinder||Mixer Grinder||Fruice Blender Grinder|
|Voltage||220V -230V AC||220V -230V AC||220V -230V AC||220V -230V AC||220V -230V AC||220V -230V AC|
|Speed||22000 RPM||22000 RPM||22000 RPM||22000 RPM||22000 RPM||18000 RPM|
|Warranty||1 year||1 year||1 year||1 year||1 year||1 year|
|Country||Made in India||Made in India||Made in India||Made in India||Made in India||Made in India|
In conclusion, when you are looking to buy a mixer grinder, there are a number of important features to consider. Consider the power of the motor, the number and size of jars, speed settings, blades, ease of use, noise level and warranty offered. Take the time to do your research and compare different models to find the best mixer grinder for your needs.
What can you use a table top grinder for?
Depending on the bond and grade of the grinding wheel, it may be used for sharpening cutting tools such as tool bits, drill bits, chisels, and gouges. Alternatively, it may be used to roughly shape metal prior to welding or fitting.
What are the three basic types of surface grinders?
Surface grinding is the most common type of grinding process. It is a fixture in heavy industry where various kinds of metal and non-metal objects need to be refined and smoothed for a finishing process. This is most often seen in the automotive industry.
- A surface grinder consists of a table, above which is held the abrasive wheel.
- A device called a chuck holds in place the item being worked on, referred to as a workpiece.
- Chucks can be magnetic, vacuum, or mechanical, depending on the workpiece composition.
- There are three basic types of surface grinders : horizontal-spindle, vertical-spindle, single disc grinders and double-disc grinders.
Each machine is best suited to certain items. The essential difference is in how the grinding wheel makes contact with the workpiece. Horizontal-spindle grinders, also called peripheral grinders, work best for high-precision work, such as angled or tapered surfaces and slots or recessed surfaces.
- The flat edge of the wheel -the periphery- makes contact with the piece.
- Pins, pistons, connecting rods, and bearing races are examples of components ground using this type of machine.
- Vertical-spindle grinders, or wheel-face grinders, are typically used for fast material removal.
- The face of the grinding wheel is lowered onto the workpiece below it.
Vertical-spindle grinders work best for stators, wafers, rotors, gears, inner rings and inner plates, and stops and spacers. Single-disc grinders and double-disc grinders appear as both horizontal-spindle and vertical-spindle styles. Disc grinders have a larger contact area between the grinding surface and the workpiece, and can grind both sides at once.
- Some rotors, plates, spacers, gears, and washers can be put into disc grinders.
- Oyo Machinery USA offers three models: R Series vertical spindle/rotary table grinders, HD Series horizontal spindle type double disc grinders, and KVD Series vertical spindle type double disc grinders.
- Each series can be adapted with several feed styles to accommodate all types of production.
Koyo Machinery USA is a world leader in the development and manufacture of custom centerless, surface, and specialty grinders. Contact us today to find out what we can do for you!
What is a wet bench grinder?
WET STONE GRINDERS – Now if after all of this you’re still concerned of overheating your tools, the Wet Stone Grinder is a one-stop solution for tool sharpening. Wet Stone Grinders use water to lubricate and cool a large, wide, slow-spinning grinding stone, leaving no risk of overheating your metal or compromising its temper whatsoever.