Dressed For Success. Dressing diamond grinding wheels

Dressed For Success

Here are some tips for getting the best performance from a grinding wheel.

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The key to maximizing the performance of a production grinding application is having the right truing and dressing tool and using it correctly. In fact, a skillful operator with a quality dressing tool and good dressing technique can often improve the performance of a wheel that may not be the optimum wheel for the application. This skill is particularly important in shops where it isn’t practical to have a special wheel for each operation.

Dressing is the process of sharpening the abrasive elements of the wheel. The process breaks down the bond and removes dull abrasive grains to expose new and sharp abrasive particles. Dressing also removes tiny pieces of material from the pores of the wheel face to prevent wheel loading, which can cause vibration and leave burn marks on the workpiece.

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Without proper dressing, it’s impossible to achieve the best consistency and adherence to specs from even the highest quality abrasive wheel. In fact, when you invest in top-quality grinding wheels, it becomes even more important to dress them properly in order to capture the quality and performance benefits.

Truing is a companion wheel-preparation process performed at the same time as dressing on conventional wheels. With superabrasive wheels, the two processes are accomplished separately, with truing performed first. In superabrasive wheel applications, truing is done with a tool or roll, while dressing often employs a vitrified dressing stick in a secondary operation.

It’s important to ensure that the spindle bearings are warm—as warm as normal grinding conditions—prior to truing and dressing. This avoids both the loss of part geometry and abnormal wear of the tool and the wheel. Tools should be handled carefully because diamond is brittle and susceptible to cracking and chipping if the tool is dropped.

Because a diamond dresser is itself a cutting tool, it has to be sharp to do its job. Dull dressing tools glaze the wheel face to produce a dull wheel. To maintain a well-defined and sharp diamond point, rotate the single-point or cone-point tool 1/8 turn at regular intervals. The frequency of these rotations will depend on how often you dress, but a minimum of once per day is a good rule of thumb. Chisel and form tools are typically flipped 180 degrees one time during their life cycles.

Most cylindrical grinders are arranged so that the workpiece and the grinding wheel are on the same horizontal line. The point where the circumference of the work touches the circumference of the wheel is called the work/wheel contact. The diamond tool should dress the wheel as close to this point as possible. On internal grinders, the orientation of the diamond to the work/wheel contact is even more important.

Take Light Cuts

There is always the temptation to take too deep a cut in an effort to reduce dress times. This is false economy. Use the correct amount of infeed instead. Too heavy an infeed overheats the tool and reduces tool life, and valuable grinding abrasive is lost. The net result is a dull tool producing a dull or closed wheel. Dress the minimum amount necessary to restore the wheel’s geometry and cutting action, taking off only what you need.

With single-point dressing tools, approach the grinding wheel at a 10- to 15-degree drag angle. This will create a sharpening effect for the tool when the tool is rotated. Multi-point (impregnated) tools do not require a drag angle. Instead, approach the wheel with full-face contact.

The traverse rate, which is the speed at which the tool moves across the wheel, is critical to achieving the desired part finish and metal removal rate. A traverse rate too slow tends to close up the wheel, compromising part finishes and metal removal rates. The slow rate can also cause the wheel to vibrate and burn the workpiece. Faster traverse rates create an open wheel face, removing more metal and accelerating part finishing.

Stay Cool

Proper use of coolant speeds dressing and makes it more effective. As a rule of thumb, use a 3/8-inch diameter stream of coolant to remove excessive heat from the tool during dressing, extending tool life. Arrange the coolant nozzle to either flood the entire wheel face or follow the diamond as it moves across the wheel. Never allow the tool to go in and out of the coolant flow while it is in contact with the wheel. Diamonds may crack or cleave during extreme temperature changes.

Filter the coolant to avoid recirculating dirt or chips, which can load the wheel and result in a need for more frequent dressing. Dress dry only when you plan to grind dry (and in such a case, allow frequent intervals for the diamond to cool). After shutting off the coolant flow at shift’s end, let the wheel idle for a few minutes. This will help prevent wheel breakage.

Vibration Is The Enemy

It is also crucial to minimize vibration during wheel dressing to avoid diamond marks, gouging and damage to the tool. This means maintaining proper balance, which begins with the grinding wheel structure itself. Density variations and overall wheel geometry affect a wheel’s inherent balance, so selection of a well-made product is essential.

Assuming a quality grinding wheel, proper installation will keep the wheel in balance. Follow the manufacturer’s directions by, for example, following the mount-up arrows on the wheel to locate the light point. Mounting the wheel with the mount-up arrow pointing upward minimizes imbalance after dressing. Even distribution of coolant also helps to maintain balance.

To further avoid vibration, be sure the tool is tight in its holder and rigidly supported with a minimum amount of overhang. If the diamond tool is not securely held, vibration will cause chatter, diamond marks, gouging and damage to the tool.

Conclusion

The importance of proper truing and dressing cannot be too strongly emphasized. A grinding wheel needs to be trued and dressed before it touches a piece of material. Following these procedures will help ensure that your grinding wheel produces superior results.

About the author: Debbie Simpson is product manager for diamond tools with Saint-Gobain Abrasives of Worcester, Massachusetts.

Do’s and Dont’s Of Diamond Dressing Tools

Do 1. Back off from the previous feed before inserting a new dresser. Many diamonds are damaged during initial touch-off.

Set diamond point at a 10- to 15-degree angle, pointing toward the direction of wheel rotation.

Tighten tool solidly in holder without unnecessary tool overhang.

Use coolant whenever possible. Flood tool point of contact at all times during dressing.

Start dress at the highest point of the wheel, usually the center.

Take light cuts. Maximum depth for roughing: 0.001 to 0.002 inch. For finishing: 0.0005 to 0.001 inch.

Use the correct traverse rate. The slower the traverse rate, the lower the finish.

Dress wheel at regular intervals to prevent loading the surface.

Turn tool in holder 1/8 turn in one direction at regular intervals to maintain a sharp point.

When diamond wears dull and visibly flat, have it reset or replaced.

Get the right carat size diamond for your wheel diameter. Bigger wheels require larger diamonds.

Don’t 1. Don’t hit the wheel with the diamond when placing it in the holder.

Don’t set single point tool shank towards the center of the wheel; always offset shank at 10 to 15 degrees.

Don’t quench a hot tool; it can crack the diamond. Allow diamonds adequate time to cool between dresses when dressing dry.

Don’t assume a wheel is perfectly flat. Look for its highest point for initial contact.

Don’t take more than 0.001 inch on wheel radius per dress pass if possible. Excessive infeed can cause premature diamond wear and often fractures the stone.

Don’t take too little off the wheel per dress pass. Wheels on older or weaker machines may not clean up.

Don’t leave the tool in one position too long. You’ll wear a flat that will glaze the wheel, overheat and damage the stone. Rotate the tool at least once per day.

Don’t continue using a worn or damaged tool. Have it reset or replaced.

Don’t rough dress at excessive infeed and traverse rates, then slow for finish dressing. This damages the diamond(s). Use the same rates when rough and finish dressing if possible.

Dressing is an essential part of the grinding process

The importance of proper truing and dressing of grinding wheels cannot be ignored. Dressing restores the grinding wheel to its original state, and during this process, swarf is removed, as are any abrasive grains that have been dulled.

Diamond dressing tools use the hardness of the diamond to restore the grinding wheel’s face. The quality of a finished part often depends upon the selection of the correct tool. Also, using these tools properly is paramount because improper dressing will cause a wheel’s performance to be substandard.

Why Dress the Wheel?

Grinding is essentially a cutting operation. Rather than a single-point cutting operation, such as turning with a carbide insert, grinding uses many small cutting edges on the grains of the grinding wheel to remove material from the workpiece. These grains —or teeth—must be kept sharp to remove material at the highest rate possible while also creating the best surface finish.

During dressing, the hard diamond point breaks the grains on the wheel or removes dull grains entirely, thereby creating new edges. The spaces between the grains are also cleaned of dust during this process.

Taking several steps can help ensure that a proper dressing occurs.

Ensure the machine is warmed up. When spindle bearings are cold, wheel position and balance may be different than when they are warm. Creating a situation that mimics normal grinding conditions is recommended prior to dressing the wheel.

Dressing should occur at constant speeds, both in terms of traverse rate and RPMs.

The traverse rate is typically determined by the type of grinding that is being performed. A slow traverse gives a high finish, but one that is too slow will “glaze” the wheel. Fast traverse rates will create a wheel that cuts more freely.

If possible, the last pass should be performed in the opposite direction from the previous one. This will help eliminate diamond marks.

During dressing, the wheel’s RPMs should be as close as possible to the normal operating speed, but not higher. However, when dressing the regulating wheel of a centerless grinder, set the RPMs as high as possible.

Position the dressing tool correctly. The tool should be positioned at or near the horizontal center of the grinding wheel. If the diamond is too high or too low, the wheel face will become tapered. This is of greater importance on internal grinders than on external ones.

In grinding, the point at which the workpiece meets the circumference of the wheel is called the work/wheel contact. Diamond tools should dress the wheel as closely as possible to this area.

Positioning the tool correctly also means employing a drag angle. The right way to do this is to point the tool in the same direction as the grinding wheel’s travel. Angling the tool in this manner reduces chatter and prevents gouges from appearing in the wheel. During external grinding, drag angles typically should be 10 to 15 degrees from the wheel’s centerline and contact point.

Approaching from other angles, or from the side, may actually damage the diamond.

Eliminate vibration. When the tool is tight in its holder, vibration will be reduced, as will chatter, marks on the wheel, and gouging.

Cut lightly. Removing less than 0.001 in. for finishing is recommended. Roughing cuts can be heavier.

While the temptation may be there to take deep cuts to make the process go faster, deep cuts have a tendency to leave diamond marks on the wheel, which are then transferred to the workpiece. Too much heat also can be generated, causing increased wear on the diamond.

Use lots of fluid. While wheels can be dressed with or without grinding fluid, the choice depends on whether fluid is being used during the actual grinding process. The rule of thumb says that if grinding dry, dress dry; if grinding wet, dress wet. In dry dressing, passes should be performed in three- to five-second intervals to allow the diamond to cool. This will prolong tool life and reduce burning of the wheel.

Coolant nozzles also need to be pointed in a manner that allows fluid to reach the entire face of the wheel. Coolant also should be filtered.

Use sharp tools. Turning the diamond frequently ensures a sharp point is being used. Dull tools will pack the wheel’s pores with particulate, creating a dull surface. It’s simple: Blunt diamonds just will not produce the same results as sharp ones.

Handle with care. Dressers are important to the overall effectiveness of the grinding operation and should be handled appropriately. Bumping the tool into the wheel creates shock to the diamond and may result in damage.

Diamond Tools: Eliminating Chatter

By William James, Stationary Tool Product Engineer, Saint-Gobain Abrasives

Chatter can be defined as the point at which a grinding wheel can no longer remove a given amount of material, in a given amount of time. There are many different causes and types of chatter. One of the most prevalent caused by stationary dressing tools is bar chatter.

For tools with single points:

• New tools seldom cause chatter.
• Worn or dull tools cause chatter.
• Moving a tool too slowly when dressing can cause chatter as it dulls the wheel.
• The tips of single-point tools develop wear flats over time. The larger the wear flats, the more likely chatter will occur.
• Rotating the diamond radially a quarter turn in the same direction once per shift helps the diamond maintain a sharp point. This extends tool life, and also helps prevent chatter.
• Removing excessive amounts from the wheel when dressing can dull the tool, thus creating chatter.
• Using tools with undersized carat weight diamonds causes diamonds to overheat, soften, and go dull, again creating chatter.
• Dressing without coolant dulls the diamond faster and often induces chatter.
• Use the correct tool for your wheel. Incorrect tools will wear prematurely, dull, and cause chatter.
• Grit tools must move three times faster than single-point tools across the wheel to avoid overheating and the likelihood of chatter. Increasing the speed at which the tool moves across the wheel sharpens the wheel and prevents chatter.
• The slower a tool moves across the wheel, the lower the finish and more likely the chatter.
• Chatter and burn are partners. Actions taken to eliminate one problem often works for the other.

Dressing/conditioning diamond and CBN Borazon grinding wheels

Dressing/conditioning diamond and CBN Borazon grinding wheels, resin- and metal-bond only, is one of the most overlooked processes. And most dressing is done insufficiently.

The simplest and basic dressing process is to use a white aluminum oxide dressing stick. Maximum exposure is necessary to optimize the wheel performance. Because of the many grades of carbides and the combination of wheel specifications, the grinding process does not always allow the wheel to stay open and exposed. The same with CBN Borazon wheels. There are so many steel alloys harder than 54 HRC and so many wheel bonds (resin and metal bonds only), particle sizes and hardnesses that it is sometimes necessary to even dress a CBN wheel.

Hand dressing with a DIT Type A dressing stick (aluminum oxide) is the simplest and most basic process.

1st: Use the proper grit size and abrasive dressing stick For wheels with a mesh size of 270 and coarser, use a Type A 220-grit stick. For wheels with a mesh size of 320 and finer, use a Type AF 320-grit stick.

Generally, an aluminum-oxide stick is used for dressing polyimide, resin, and some hot-pressed vitrified-bond wheels. Silicon-carbide sticks are used on metal, some vitrified-metal, and hot-pressed vitrified bonded wheels. Black silicon carbide is usually used.

Use an SC 80-grit stick for wheels with a mesh size under 270, and a SCF 320-grit is for mesh sizes 320 and finer. A black silicon-carbide stick is harder than aluminum oxide and still some operators prefer aluminum oxide even on tougher bond systems. Since there are so many different grinding applications, one has to try what is the most effective stick. When dressing cold-pressed vitrified-bond wheels, extreme care is to be used to dress very lightly and at a maximum 1” length of stick. Cold-pressed vitrified bonds have a built-in porosity.

2nd: Soak the dressing stick in water Use only a stick which is thoroughly soaked Why? A soaked, wet stick does not grind off as easily as a dry one. Also because it is wet, you have greater control of the removal of the bond. In addition, you will not get abrasive dust all over yourself and the machine.

3rd: Dress at non-grinding speeds Before pushing the stick into the wheel, turn off the power. As soon as the power is turned off, shove the stick slowly straight into the wheel until it comes to a stop. Why? As the wheel slows down, it acts softer and therefore it will erode easier and is more controllable. Or, if possible, reduce the rpm so the cutting speed is 1,000 sfm.

4th: Do not move the stick sideways In tooth type steel saw blades there are gullets, some larger and some smaller. A grinding wheel is similar. Larger mesh sizes have more clearance. small mesh sizes have smaller chip clearances. But by moving the stick sideways, the bond on the side of the particle will be eroded. This will weaken the particle bond so only plunge straight for optimal results.

5th: New wheels always need dressing They usually need some truing also. so with CBN Borazon, as they must grind more concentrically to consistently make the correct chips. Even if a wheel is dressed open at the factory when they are mounted and trued they then will need dressing.

6th: Other dressing procedures A. A speed control which changes speed of the grinding wheel to a lower rpm will make the wheel act softer and this will open up the chip clearance. B. An air jet abrasive stream will optimize automatically the exposure of the particle. C. An automatic dressing device which pushes a dressing stick into the wheel. D. A motorized device that trues and dresses at the same time. E. A diamond cup wheel or roll, which trues and dresses at the same time the parts are being ground (continuous dress). F. A computer-aided grinding system monitor, which senses the energy level of the grinding process and changes the infeed rate and rpm automatically.

Dressing of coated (plated and/or brazed) diamond wheels is a marginally effective way of cleaning out scale and swarf. Use a 220-grit stick for 500 mesh and coarser or a wire brush.

Dressing of coated (plated) CBN Borazon wheels. This is not effective in dressing out a steel loaded wheel. Usually a loaded coated wheel cannot be opened up! Even abrasive blasting could destroy the bond. Try a wire brush under power.

Note that one of the biggest misconceptions is that dressing reduces the life of the wheel. A loaded wheel grinds with greater grinding pressure and therefore gets a lower grinding ratio.

abrasive

Substance used for grinding, honing, lapping, superfinishing and polishing. Examples include garnet, emery, corundum, silicon carbide, cubic boron nitride and diamond in various grit sizes.

alloys

Substances having metallic properties and being composed of two or more chemical elements of which at least one is a metal.

aluminum oxide

Aluminum oxide, also known as corundum, is used in grinding wheels. The chemical formula is Al2O3. Aluminum oxide is the base for ceramics, which are used in cutting tools for high-speed machining with light chip removal. Aluminum oxide is widely used as coating material applied to carbide substrates by chemical vapor deposition. Coated carbide inserts with Al2O3 layers withstand high cutting speeds, as well as abrasive and crater wear.

chip clearance

In milling, the groove or space provided in the cutter body that allows chips to be formed by the inserts.

clearance

Space provided behind a tool’s land or relief to prevent rubbing and subsequent premature deterioration of the tool. See land; relief.

cubic boron nitride ( CBN)

Crystal manufactured from boron nitride under high pressure and temperature. Used to cut hard-to-machine ferrous and nickel-base materials up to 70 HRC. Second hardest material after diamond. See superabrasive tools.

cutting speed

Tangential velocity on the surface of the tool or workpiece at the cutting interface. The formula for cutting speed (sfm) is tool diameter 5 0.26 5 spindle speed (rpm). The formula for feed per tooth (fpt) is table feed (ipm)/number of flutes/spindle speed (rpm). The formula for spindle speed (rpm) is cutting speed (sfm) 5 3.82/tool diameter. The formula for table feed (ipm) is feed per tooth (ftp) 5 number of tool flutes 5 spindle speed (rpm).

dressing

Removal of undesirable materials from “loaded” grinding wheels using a single- or multi-point diamond or other tool. The process also exposes unused, sharp abrasive points. See loading; truing.

grinding

Machining operation in which material is removed from the workpiece by a powered abrasive wheel, stone, belt, paste, sheet, compound, slurry, etc. Takes various forms: surface grinding (creates flat and/or squared surfaces); cylindrical grinding (for external cylindrical and tapered shapes, fillets, undercuts, etc.); centerless grinding; chamfering; thread and form grinding; tool and cutter grinding; offhand grinding; lapping and polishing (grinding with extremely fine grits to create ultrasmooth surfaces); honing; and disc grinding.

grinding wheel

Wheel formed from abrasive material mixed in a suitable matrix. Takes a variety of shapes but falls into two basic categories: one that cuts on its periphery, as in reciprocating grinding, and one that cuts on its side or face, as in tool and cutter grinding.

grit size

Specified size of the abrasive particles in grinding wheels and other abrasive tools. Determines metal-removal capability and quality of finish.

sawing machine ( saw)

Machine designed to use a serrated-tooth blade to cut metal or other material. Comes in a wide variety of styles but takes one of four basic forms: hacksaw (a simple, rugged machine that uses a reciprocating motion to part metal or other material); cold or circular saw (powers a circular blade that cuts structural materials); bandsaw (runs an endless Band; the two basic types are cutoff and contour Band machines, which cut intricate contours and shapes); and abrasive cutoff saw (similar in appearance to the cold saw, but uses an abrasive disc that rotates at high speeds rather than a blade with serrated teeth).

truing

Using a diamond or other dressing tool to ensure that a grinding wheel is round and concentric and will not vibrate at required speeds. Weights also are used to balance the wheel. Also performed to impart a contour to the wheel’s face. See dressing.

Grinding Wheel Dressing – Wheel Dresser Types Specification

Dressing may be broadly defined as any operation performed on a wheel face to change the nature of its cutting action.

Why Grinding Wheel Dressing Needed?

Dressing is necessary when the individual grain crystal in the wheel face become dulled and the rate of stock removal is constantly decreasing as the grinding operation is prolonged without dressing.

Dressing is also necessary when the abrasive crystals or bond pores become loaded with metal or foreign matter, since this loading seriously affects the grinding action of the wheel.

Grinding Wheel Dressing Tools ( Wheel Dressers)

1) Diamond Dressers

Diamonds for dressing and truing grinding wheels are of several types, each having different characteristics.

“Multi-point”-An arrangement of twelve small set in a single plane in such a way that all stones contact the grinding wheel face simultaneously.

“Multi-Edge”-Three diamonds set in a line one behind the other, parallels to the wheel face. This tool is applied to the grinding wheel at a “down angle” and when the stones are flattened on one side from use, the tool is turned over.

2) Star Dressers

The Huntington or star type dresser has pointed discs loosely mounted on a pin, with solid discs as separators.

This type is exclusively used for dressing coarse grit wheels for snagging and offhand grinding and also for dressing segmental surface grinding wheels. It is low cost but requires some little skill in operation.

The Huntington dresser is the most efficient tool from the point of view of removing metal filling in general and the abrasive wheel type dressers are next in efficiency.

3) Precision Steel Type

This is popular and frequently used in place of diamond dressers for commercial grinding on precision grinding machines.

4) Abrasive Stick Dressers

These are of two shapes – square for hand manipulation and round for magazine mounting. Magazine mounting sticks find use in forming wheels for profile grinding and for dressing and truing relatively thin wheels.

5) Abrasive Wheel Dressers

These consist of properly bonded silicon carbide wheels rotably mounted in a suitable holder with high grade bearings. They will, in many cases, entirely replace the diamond on both center and centre less types of cylindrical grinding.

Their use imparts a smooth, clean cutting face which leaves no dressing marks on the work. With a few exceptions, since coolants are not generally used with the abrasive wheel dresser.

Diamond Dressers Specification

Diamond DressersCaratUse (Diameter)

HS010	1	350-450mm
HS015	1.5	450-500 mm
HS020	2.0	600 mm above

Hindustan surface grinding Segment are a universal choice for all those customers for heavy, Rapid stock removal and production work. These Segments can easily handle tolerance operations and are generally preferred in such uses only.

FAQs about Dressing a Grinding Wheel

Dressing of a grinding wheel refers to the process of re-shaping the abrasive particles on the surface of the wheel to restore its cutting ability. This is done by using a “dressing tool” which is typically a separate tool or a device built into the grinding machine. Dressing can be done manually or automatically and it can be done on a regular basis to maintain the quality of the grinding wheel.

Dressing and truing are both processes used to maintain the quality and condition of a grinding wheel, but they are different in terms of their specific purpose and the methods used to accomplish it.Dressing refers to the process of reshaping the abrasive particles on the surface of the wheel to restore its cutting ability. This is done by using a dressing tool, which is typically a separate tool or a device built into the grinding machine. The dressing tool removes worn abrasive particles, revealing new sharp edges and creating a uniform surface on the wheel.

Truing, on the other hand, is the process of making sure that the wheel is running concentrically and true. This is accomplished by using a truing tool, which is also typically a separate tool or a device built into the grinding machine. Truing is done to correct any run-out or wobbling of the wheel, and it is done to ensure that the wheel is round, straight and that its running face is square to the wheel axis.

Dressing a grinding wheel involves the following steps:1- Secure the wheel in the grinding machine and turn on the machine.2- Hold the dressing tool (e.g. a diamond dresser) against the wheel, with the tip touching the surface of the wheel.3- Apply light pressure to the tool and move it across the wheel surface in a uniform manner.Continue this process until the desired shape or condition is achieved.4- Inspect the wheel for any remaining defects and repeat the process if necessary.5- Turn off the machine and carefully remove the wheel.

It’s important to note that the specific steps and tools used may vary depending on the type of grinding wheel and the machine being used. It’s always recommended to check the machine and wheel manufacturer’s instructions before attempting to dress a wheel.

Also, it’s very important to use the correct type of dressing tool, as using the wrong one may damage the wheel or cause safety hazards. And also, it’s very important to wear proper personal protective equipment (PPE) such as eye protection and gloves while dressing a wheel.

A wheel dresser, also known as a dressing tool, is a tool or device used to dress or reshape the abrasive particles on the surface of a grinding wheel. The purpose of dressing a wheel is to restore its cutting ability and create a uniform surface on the wheel. This ensures that the wheel cuts consistently, reduces chatter and vibration and increases the wheel’s lifespan.Wheel dressers come in a variety of types and designs, each suited for specific types of grinding wheels and machines. The most common types of wheel dressers are:1- Single-point diamond dressers: These are used to create a specific shape on the wheel, and are typically used for precision grinding operations.2- Multi-point diamond roll dressers: These are used to true the wheel surface and are typically used for heavy-duty grinding operations.3- Stick or star dressers: These are made of tungsten carbide or steel and are used to true and maintain the shape of the wheel.

The frequency of dressing a grinding wheel depends on the type of wheel, the material being ground, and the grinding conditions. However, as a general rule of thumb, the wheel should be dressed at least once for every 10 grinding sessions.

The dressing ratio for a grinding wheel is the ratio of the volume of abrasive material removed from the wheel to the volume of dressing material used for the process. This ratio is an important parameter that indicates the efficiency of the dressing process.

Grinding wheels should be regularly dressed to maintain their geometry and cutting efficiency. Dressing helps to remove dull abrasive grains and expose fresh grains, which enhances the grinding performance and prolongs the wheel life.

Overlap ratio in dressing is the ratio of the width of the dressing tool to the width of the grinding wheel. This parameter affects the quality and efficiency of the dressing process. A higher overlap ratio means that more material is removed from the wheel per pass, which leads to a more aggressive dressing action but can also result in higher dressing forces and increased risk of wheel damage.

Silicon Carbide Grinding Wheel Dresser

CRATEX rubber-bonded silicon carbide dressing stick for grinding wheels is ideal tool for truing, dressing and shaping different types of grinding wheels including CRATEX rubberized abrasive wheels. It is a perfect solution to keep your grinding wheel flat, sharp, clean and running smoothly!

With this easy to use, efficient and long-lasting dresser you’ll enhance your grinding wheel cutting and finishing performances. It’s simply a MUST for everyone who continuously uses a bench grinder.

Use CRATEX cleaning abrasive sticks and minimal effort and your grinding wheel will be in a top-notch form in just a few minutes. Simply choose the dressing wheel shape, grit and length and before you know it, your order will be on the way!

Recommended for CRATEX Large Grinding Wheels : Dressing Stick Size: 6” x 1/2” x 1/2”

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CHAPTER 1

What is Grinding Wheels Dressing

CHAPTER 3

CRATEX Dressing Stick

CHAPTER 4

What Is The Difference Between Dressing And Truing?

CHAPTER 1

Grinding wheels are tools used most often for grinding (abrasive cutting) operations. In our article dedicated to grinding wheels we already explained that grinding wheels are designed as self-sharpening tools, which means that the grinding process itself sharpens the wheel every time it’s used. Small abrasive cutting grains of the wheel become dull during the grinding process and break away from the bonding material, leaving the sharp grains exposed. However, this awesome self-sharpening ability is not quite enough, since the work material can cause it to load up, so it is necessary to occasionally dress or true the wheel to achieve satisfying results. If the wheels are not maintained, increased cutting forces and the created heat can cause damage to the surface finish and wheel breakage. Dressing is not so much important for rough grinding wheels, but you’ll need to always have a true, flat face on your wheel in case you’re doing some precision grinding.

Here’s where the grinding wheel dresser steps in. It is a handy tool used to remove the top layer of a grinding wheel in the purpose of:

• Truing it and making it concentric, which will minimize vibrations and improve the quality of the finishing operations. Loaded or clogged areas on the wheel will cause it to lose its roundness, and the loss of the roundness will eventually cause excessive vibrations of the bench grinder. The reason why the wheel loses its shape is because the clogged areas wear off at a different rate from the less loaded areas;
• Exposing fresh abrasive grains, which will enhance the cutting action. Dull grains of the wheels with extremely hard bond will usually remain in the wheel;
• Cleaning the pores between the abrasive grains, which get filled with workpiece fragments. This happens in case the workpiece has a softer grade than the one the wheel is designed for. In that case, the grains won’t break away in time and the workpiece parts will get stuck between them.

With dressing, the wheel will be good as new and ready for renewed grinding action!

CHAPTER 2

Grinding wheel dressers can be broadly divided in following categories:

• Dressing rolls and rotary tools – these dressers have rolls or wheels that are coated with diamonds;
• Dressing spindles. spindle-mounted tools that usually come with an integral brake and drive;
• Dressing sticks – or dressing blocks are made of bonded abrasives;
• Impregnated or grit dressing tools – these have a whole layer of diamond or superabrasive grains bonded in the matrix, much more sharp points than an ordinary multi-point tool. These are used in the same way as multi-points tools, but they are designed to provide a superior finish;
• Single-point dressing tools – these have only one diamond or superabrasive grit bonded in the tip and can be various: single point tools should be mounted at a 10°-15° angle to the wheel centerline while the contact point should be slightly below the centerline. The tools should point in the direction of wheel travel;
• Multi-point or Cluster dressing tools – unlike the single-point ones, cluster dressers have several diamonds or superabrasives across the dresser surface. They can be wide enough to reach across the entire cutting surface of the grinding wheel and most of them are used for straight-face dressing. They came into use mostly because they’re more affordable (instead of one large diamond they have several smaller ones).

Grinding wheel dressers used most often on bench grinders are as follows:

These are dressing bonded abrasives shaped as a stick or a block. You’ll usually use dressing blocks made from the same abrasive type as the grinding wheel, but you’ll choose a stronger bonding agent. Typical abrasives used in grinding wheel dressing sticks are aluminum oxide and silicon carbide. For resin and vitrified bond diamond and cBN wheels you should choose a dressing stick that is one or two grit sizes finer than the abrasive in the wheel. For metal bond diamond choose a stick the same grit size or one grit size coarser than the wheel abrasive.

These are heavy-duty dressers with long handles, a row of hardened free running either star-shaped cutters or wavy discs, and little ‘legs’ that are designed to go behind the tool rest. Star dressers provide a more ‘open’ texture, which is perfect for rough grinding, and they are more suitable for larger (e.g. 12″) grinders. They are consumable items that are going to wear down, so you’ll need to change the discs after they do.

These dressers have a short handle and you can find two types. Either those with a single diamond embedded in their face, or those with a lot of small diamonds embedded in a wide surface. Diamond is the hardest superabrasive used for truing and dressing conventional and superabrasive grinding wheels. It’s ideal for fine finishing cutting tools as it gives the grinding wheel a smoother finish. Although diamond dressers might seem pricey initially, rest assured you’ll get your money’s worth, since diamond is extremely durable and therefore a long-lasting tool.

When it comes to CNC grinders, four types of dressers can be used for dressing their wheels.

This is a wheel made of either high-speed steel or tungsten carbide, which is pressed against the grinding wheel while spinning at the same speed as the wheel. The dresser profile is the mirror image of the desired grinding wheel profile and cannot be adjusted, only replaced by a different profile.

This would be a crush roll which is coated with diamond grains. Diamond grains give them an advantage over regular crush rolls, because they wear more slowly.

These have a metal blade that has a single diamond embedded in the tip. A CNC program for dressing the wheel controls the wheel’s profile and is responsible for moving the dresser across the wheel’s surface.

These are sometimes called ‘pizza cutters’. A disc made of material (usually a diamond) is attached to the edge, and the grinding wheel’s profile is controlled by the CNC program used to wheel dressing as well.

CHAPTER 3

CRATEX silicon carbide grinding wheel dresser dresser is a perfect tool for dressing and truingdifferent kinds of grinding wheels including all rubber-bonded abrasive wheels. Thanks to its shape, fast cutting abrasive with a hardened bond, it’s an efficient, easy to handle and a long-lasting dressing stick that will help you achieve maximum performance from all your CRATEX rubberized abrasive wheels.

Selecting the appropriate dressing stick will depend on the size, type, speed, grit size and specification of the wheel, and of course, the workpiece material. A good advice would be to test several sticks to find the best possible solution for your needs.

RECOMMENDED: Check out CRATEX Mini Test Block Kit No.128B (shipping and handling included in the price)

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Dressing sticks are used for dressing and truing bench and pedestal grinder wheels. You’ll only need your hand and a dressing stick to perform the dressing which is done by moving the stick back and forth against the wheel face. In case the movement is fast, so will be the metal removal, which will cause rougher finishes on the workpiece. If the movement is slower, the grinding wheel face will be smoother, there will be less metal removal and the surface finish on the workpiece will be finer.

CRATEX dressing sticks are a perfect solution to keep your grinding wheel flat, sharp, clean and running smoothly! A MUST for everyone who continuously uses a bench grinder!

Order Square Sticks

CHAPTER 4

Both dressing and truing must be conducted in the purpose of creating satisfactory work. Both operations remove material from the grinding wheel. While dressing relates to a surface finish maintenance, truing relates to the loss of form control due to the excessive edge wear.

Although sometimes together referred to as ‘conditioning’, they mean two different operations. Conventional grinding wheels that are inexpensive can be trued and dressed at the same time and the process can be repeated periodically. However, superabrasive grinding wheels, like CBN or diamond wheels, are a serious investment and require much more attention to dressing and truing separately.

Truing is done when a new wheel is installed and before it’s used for the first time and is necessary for precision grinding. The purpose of truing is to bring every point of the grinding surface concentric with the machine spindle (to establish concentricity) and to introduce a form (shape) into a wheel. No matter how precisely manufactured, there will be a slight gap between the wheel bore and the machine spindle. Even if the gap is one thousand of a millimeter, problems like chatter marks will occur if the wheel is not trued to the center of the spindle. Conventional grinding wheels can be trued easily with a diamond cutter that is harder than the wheel, while the superabrasives cannot be cut and must be ground to size. This is done by using a sintered diamond roller or by traversing a conventional grinding wheel. Many like to use a brake-controlled truing device called BCTD which turns more slowly and provides a more precise and controllable truing. After the truing process, the wheel surface is smooth and closed, and since there are no abrasive grits exposed, the wheel can’t perform cutting.

Dressing is the process that comes after truing (especially in the case of superabrasives) and it represents grinding wheel sharpening by exposing abrasive grits above the bond. In other words, removing small chips of workpiece lodged in the wheel surface or removing dull abrasives which returns the wheel to its original dimensions and provides crystal exposure. The wheel surface after dressing is open with grits exposed.

• AIR TOOLS
• Rubberized Abrasives
• MX Abrasives
• Brightboy
• Regulating Wheels
• Spedecut

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