Grinding dresser

Last updated November 25, 2022

A grinding dresser or wheel dresser is a tool to dress (slightly trim) the surface of a grinding wheel. Grinding dressers are used to return a wheel to its original round shape (to true it up), to expose fresh grains for renewed cutting action (including cleaning away clogged areas), or to make a different profile (cross-sectional shape) on the wheel's edge. Utilizing pre-determined dressing parameters will allow the wheel to be conditioned for optimum grinding performance while truing and restoring the form simultaneously.

Purpose

The objective of dressing the wheel is to:

True the wheel by knocking abrasive particles from the wheel's surface and making the wheel concentric. This minimizes vibration and improves surface finish, eliminating the vibration of the out-of-balance wheel across the workpiece's surface. It is not unusual for grinding wheels to become out of round with use. This is partially from loaded (clogged) areas of the wheel wearing at different rates from less loaded areas. It can also be exacerbated by grinding when the wheel is not under power, such as using the work to apply braking action to the wheel to stop it from coasting. Dressing restores the roundness. When bench grinders vibrate excessively, it is usually because the wheels have worn out of round and are thus out of balance. Truing them by dressing resolves this problem.
Dislodge these abrasive particles to expose fresh abrasive from the wheel's surface. Each abrasive grain is a small cutting tool; a worn grain has its edges dulled and loses its effectiveness. Exposing the fresh grains is thus a sharpening process. Glazing of the wheel is evidence of rounded grains and is noticeable by a reflective surface on the spinning wheel.
Clean the wheel. If a workpiece is softer than the grade for which the wheel is designed, the abrasive particles will not be dislodged in time to present fresh, sharp grains. The wheel therefore appears to lose its edge especially as the pores between grains fill with fragments of the workpiece. The wheel is then said to be loaded. This is one reason why the selection of wheel is extremely important.
Condition the wheel. Establish the optimum dressing parameters to achieve the part tolerance/finish requirements. Truing and conditioning of the wheel will happen simultaneously so understanding the wheel condition needed to achieve the desired part condition is critical.

Types

Star or disc wheel dresser GrindingWheelDresserDisc.jpg — Star or disc wheel dresser

Star dressers— A long handled tool with a row of free running, hardened and serrated, wavy discs or star-shaped cutters running at right angles to the handle. These are presented to the grinding wheel as power is turned off and the wheel slows down. Force is applied to the face of the slowing wheel with the result that the hardened discs match speed with the face of the wheel allowing the fingers or undulating surface of the dresser, to knock the abrasive grains out.

Diamond dressers GrindingWheelDressersDiamond.jpg — Diamond dressers

Diamond dressers— Shorter handled diamond tools that either have a matrix of small diamonds bonded to a broad surface on the end of the dresser (top image) or a single diamond mounted in their face (lower image). As the diamond is introduced to the wheel's face, the harder diamond remains attached and the looser grains fall away.
Dressing sticks— A stick of hard material, usually made from the same materials (silicon carbide) but with a stronger bonding agent. NorBide is one brand of dressing stick made by Norton Abrasives from boron nitride.^[1]

Also an abrasive wheel type that has a small "grinding wheel" in a holder that is held against the spinning grinding wheel to dress and clean the face of the grinding wheel.

Grinding complex shapes

Four types of dressers are used to dress the wheels of CNC grinders used for grinding complex shapes. This type of dresser is mainly in use on CNC grinding machine tools to automatically dress the grinding wheel via computer control in specialist areas requiring complex shapes such as grinding bearing raceways.

Stationary dressers— a stationary dresser can have multiple diamonds hand set or a (mesh) across a given width. These type tools are typically used to dress straight faced wheels. Stationary tools can also be a single diamond brazed into the tip and ground to a specific radius size. A CNC dressing program will utilize this specific tool nose radius offset and move it across the face of the wheel, moving in and out to create the desired profile. The grinding wheel's profile is controlled by the CNC program used to dress the wheel, rather than by the profile of the dresser itself.
Crush rolls— a crush roll is a high-speed steel or tungsten carbide wheel. Its profile is the mirror image of the desired profile of the grinding wheel. It is forced against the grinding wheel, while spinning at the same surface speed as the grinding wheel. Doing so breaks the bond between the abrasive particles on the surface of the wheel, exposing a new surface as particles fall away. One disadvantage is that the wheel profile cannot be adjusted except by replacing the roll with one having a different profile.
Diamond dressing rolls— a diamond dressing roll is a dressing roll coated with diamond particles. It wears more slowly and less wear mean they can be used to achieve tighter tolerances than plain crush rolls.
Rotary dressers— a rotary dresser (sometimes referred to as a pizza-cutter dresser) is a disc with a hard material - usually diamond - attached to the edge. The grinding wheel's profile has a specific radius size and is controlled by the CNC program used to dress the wheel, rather than by the profile of the dresser itself.^[2]

Wheel Conditioning Proper wheel conditioning is a critical part of any grinding process. The condition of the wheel will determine the wheel's ability to meet the part finish requirements and metal removal rate capabilities. The grains in the wheel can be sheared to create a smooth condition or fractured to create a course open condition utilizing dressing parameters.

Truing the wheel and restoring the form will happen simultaneously while you are conditioning the wheel.
Conditioning a wheel with a stationary tool or a rotary dresser/pizza cutter are the same if you are working with a known radius tip.
When using a stationary tool or a rotary dresser, the traverse rate across the wheel face will determine the wheel condition.
Slower rates give a finer finish and faster rates give a courser finish.
Conditioning the wheel with a shaped diamond dressing roll requires the roll to be plunged into the grinding wheel at a predetermined speed and infeed rate.
Controlling the speed ratio and infeed rates are a critical part of acquiring and maintaining the desired wheel condition.
Counter-Directional dressing will sheer the grains and create a smooth wheel face.
Uni-Directional dressing will fracture the grains and create a rough wheel face.

Skate sharpening

Grinders used for sharpening skate blades typically have one or more thin grinding wheels mounted on vertical spindles, with a single-diamond dresser mounted on a gymbal with a horizontal axis level with the centerline of the wheel, so it can swing above and below the plane of the wheel, producing a convex grinding surface of a predetermined radius. This allows the blade to be sharpened to a specified hollow, typically very deep for hockey skates, very shallow for skates used for school figures, and moderate for skates used for freestyle skating.

Related Research Articles

An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflective surface, the process can also involve roughening as in satin, matte or beaded finishes. In short, the ceramics which are used to cut, grind and polish other softer materials are known as abrasives.

<span class="mw-page-title-main">Grinding machine</span>

A grinding machine, often shortened to grinder, is a power tool used for grinding. It is a type of machining using an abrasive wheel as the cutting tool. Each grain of abrasive on the wheel's surface cuts a small chip from the workpiece via shear deformation.

<span class="mw-page-title-main">Bench grinder</span> Grinding machine

A bench grinder is a benchtop type of grinding machine used to drive abrasive wheels. A pedestal grinder is a similar or larger version of grinder that is mounted on a pedestal, which may be bolted to the floor or may sit on rubber feet. These types of grinders are commonly used to hand grind various cutting tools and perform other rough grinding.

The phrase speeds and feeds or feeds and speeds refers to two separate velocities in machine tool practice, cutting speed and feed rate. They are often considered as a pair because of their combined effect on the cutting process. Each, however, can also be considered and analyzed in its own right.

Grinding wheels contains abrasive compounds for grinding and abrasive machining operations. Such wheels are also used in grinding machines.

<span class="mw-page-title-main">Tool and cutter grinder</span>

A Tool and Cutter Grinder is used to sharpen milling cutters and tool bits along with a host of other cutting tools.

<span class="mw-page-title-main">Turning</span> Machining process

Turning is a machining process in which a cutting tool, typically a non-rotary tool bit, describes a helix toolpath by moving more or less linearly while the workpiece rotates.

In the context of machining, a cutting tool or cutter is typically a hardened metal tool that is used to cut, shape, and remove material from a workpiece by means of machining tools as well as abrasive tools by way of shear deformation. The majority of these tools are designed exclusively for metals. There are several different types of single edge cutting tools that are made from a variety of hardened metal alloys that are ground to a specific shape in order to perform a specific part of the turning process resulting in a finished machined part. Single edge cutting tools are used mainly in the turning operations performed by a lathe in which they vary in size as well as alloy composition depending on the size and the type of material being turned. These cutting tools are held stationary by what is known as a tool post which is what manipulates the tools to cut the material into the desired shape. Single edge cutting tools are also the means of cutting material performed by metal shaping machines and metal planing machines which removes material by means of one cutting edge. Milling and drilling tools are often multipoint tools. Drilling is exclusively used to make holes in a workpiece. All drill bits have two cutting edges that are ground into two equally tapered angles which cuts through the material by applying downward rotational force. Endmills or milling bits, which also cut material by rotational force. Although these tools are not made to put holes in a workpiece. They cut by horizontal shear deformation in which the workpiece is brought into the tool as it's rotating. This is known as the tool path which is determined by the axis of the table that is holding the workpiece in place. This table is designed to accept a variety of vises and clamping tools so that it can move into the cutter at various angles and directions while the workpiece remains still. There are several different types of endmills that perform a certain type of milling action.

Superfinishing, also known as micromachining, microfinishing, and short-stroke honing, is a metalworking process that improves surface finish and workpiece geometry. This is achieved by removing just the thin amorphous surface layer left by the last process with an abrasive stone or tape; this layer is usually about 1 μm in magnitude. Superfinishing, unlike polishing which produces a mirror finish, creates a cross-hatch pattern on the workpiece.

A diamond tool is a cutting tool with diamond grains fixed on the functional parts of the tool via a bonding material or another method. As diamond is a superhard material, diamond tools have many advantages as compared with tools made with common abrasives such as corundum and silicon carbide.

Die grinders and rotary tools are handheld power tools used for grinding, sanding, honing, polishing, or machining material. All such tools are conceptually similar, with no bright dividing line between die grinders and rotary tools, although the die grinder name tends to be used for pneumatically driven heavy-duty versions whereas the rotary tool name tends to be used for electric lighter-duty versions. Flexible shaft drive versions also exist.

Centerless grinding is a machining process that uses abrasive cutting to remove material from a workpiece. Centerless grinding differs from centered grinding operations in that no spindle or fixture is used to locate and secure the workpiece; the workpiece is secured between two rotary grinding wheels, and the speed of their rotation relative to each other determines the rate at which material is removed from the workpiece.

Abrasive machining is a machining process where material is removed from a workpiece using a multitude of small abrasive particles. Common examples include grinding, honing, and polishing. Abrasive processes are usually expensive, but capable of tighter tolerances and better surface finish than other machining processes

Ultrasonic machining is a subtractive manufacturing process that removes material from the surface of a part through high frequency, low amplitude vibrations of a tool against the material surface in the presence of fine abrasive particles. The tool travels vertically or orthogonal to the surface of the part at amplitudes of 0.05 to 0.125 mm. The fine abrasive grains are mixed with water to form a slurry that is distributed across the part and the tip of the tool. Typical grain sizes of the abrasive material range from 100 to 1000, where smaller grains produce smoother surface finishes.

Grinding is a type of abrasive machining process which uses a grinding wheel as cutting tool.

Honing is an abrasive machining process that produces a precision surface on a metal workpiece by scrubbing an abrasive grinding stone or grinding wheel against it along a controlled path. Honing is primarily used to improve the geometric form of a surface, but can also improve the surface finish.

Electrochemical grinding is a process that removes electrically conductive material by grinding with a negatively charged abrasive grinding wheel, an electrolyte fluid, and a positively charged workpiece. Materials removed from the workpiece stay in the electrolyte fluid. Electrochemical grinding is similar to electrochemical machining but uses a wheel instead of a tool shaped like the contour of the workpiece.

Surface grinding is done on flat surfaces to produce a smooth finish.

Flat honing is a metalworking grinding process used to provide high quality flat surfaces. It combines the speed of grinding or honing with the precision of lapping. It has also been known under the terms high speed lapping and high precision grinding.

Grinding wheel wear is an important measured factor of grinding in the manufacturing process of engineered parts and tools. Grinding involves the removal process of material and modifying the surface of a workpiece to some desired finish which might otherwise be unachievable through conventional machining processes. The grinding process itself has been compared to machining operations which employ multipoint cutting tools. The abrasive grains which make up the entire geometry of wheel act as independent small cutting tools. The quality, characteristics, and rate of grinding wheel wear can be affected by contributions of the characteristics of the material of the workpiece, the temperature increase of the workpiece, and the rate of wear of the grinding wheel itself. Moderate wear rate allows for more consistent material size. Maintaining stable grinding forces is preferred rather than high wheel wear rate which can decrease the effectiveness of material removal from the workpiece.

References

↑ "NorBide Boron Nitride Dressing Stick".
↑ "Norton Winter" (PDF).

Rowe, Brian. Principles of Modern Grinding Technology (2nd ed.). Elsevier.
Hitchiner, Mike. Handbook of Machining With Grinding (2nd ed.). Taylor and Francis Group.
Hagan, John. "Optimizing Grinding and Dressing With (Dressing Speed Ratio) Parameters".{{cite journal}}: Cite journal requires |journal= (help)

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[1] "NorBide Boron Nitride Dressing Stick".

[2] "Norton Winter" (PDF).

[1]

[2]