January 24, 2022

How do CNC grinders grind tapers?

A taper grinding CNC machine is essential in grinding taper bores of milling or drilling. The wheel and the object are rotated, thus machining the outer periphery of the workpiece.

Types of grinding process

We now have advanced grinding machines in design rigidity and construction. We have a variety of grinding processes performed on different metallic materials to get the best products. Below are some of the other processes

  • Surface grinding

Surface grinding is a famous grinding method used in a range of fields. Surface grinding involves using a vertical axis grinding machine or horizontal axis grinding machine with a square table and a straight type wheel. The double-ended type gets equipped with wheels above and below as the grinding takes place. The workpiece is placed firmly on the table to perform the grinding process, and the wheel rotates at high speed.

  • Cylindrical grinding

Cylindrical grinding is also one of the most common grinding methods used widely; it uses a cylindrical grinding machine or a universal grinding machine. The cylindrical process comes in various ways, including straight cylindrical, taper, end face, and total shape grinding. The cylindrical workpiece and the wheel rotate as the outer periphery of the workpiece gets machined.

  • Centreless grinding

Cylindrical grinding involves the outer periphery of the cylindrical workpiece machined using a centerless grinding machine. The object will be supported between a fixed blade, rotating adjusting wheel, and grinding wheel. The rotation of the adjusting wheel adjusts the rotation and feed of the workpiece to smooth the outer side of the workpiece. The process is ideal for mass production because it doesn’t require a center hole in the workpiece.

  • Internal Grinding

Internal grinding uses an internal grinding machine or cylindrical grinding machine. The rotating axle wheel works on the inner surface of the workpiece whilst it’s fixed in position. Internal grinding also involves taper and taper end face grinding.

  • Gear Grinding

Gear grinding is a method of shaping the teeth of parts such as gears using a gear grinding machine. The process involves using whetstones molded with the dresser using diamond abrasive grains.

  • Contour grinding

The process uses a profile grinding machine to shape a workpiece into an arbitrary shape.

  • Plunge grinding

Plunge grinding involves using a three-point positioning method that allows you to grind the minor diameters with the grind length entirely supported. The triangular arrangement encourages the possibility of excessive grinding for complex parts. One of the benefits of plunge grinding is that it can achieve high levels of dimensional accuracy.

Plunge grinding is ideal for manufacturers who require specific aspects of small parts refinished and deburred.

Types of grinding wheels

There are different types of grinding wheels in manufacturing industries. They come in different shapes, sizes and they perform differently according to purpose.

  • Straight grinding wheels

Straight grinding wheels are ubiquitous in workshops around the world. They sharpen tools like lawnmower blades and chisels.

  • Large Diameter Grinding wheels

You can liken large diameter grinding wheels to straight wheels, but these are much larger. Large diameter grinding wheels have a large surface that grinds down the outside of round objects like carbide blanks. They are also essential in OD grinding, for example, in the Oil and Thermal Spray industries.

  • Grinding Dish wheel

Grinding dish wheels have a thinner surface edge and are very shallow. They have a narrow shape that allows them to fit into tight crevices. They are most familiar with applications that require the polishing of stone or concrete.

  • Grinding Cup wheel

Cups wheels are familiar in areas that require paint and adhesive removal. Like grinding dish wheels, they can also be essential in stone and concrete polishing, re-sharpening, and finishing other applications depending on abrasive size.

  • Cutting Face Grinding wheel

You can use cutting face wheels for cutting tiles or shaping saw teeth. Cutting Face grinding wheel cuts through a workpiece as it grinds away the material. It has a width that has a narrow edge that takes off a lot of material at once.

CNC cylindrical grinders

CNC cylindrical grinders consist of two rotating wheels, a grinding wheel, and a control wheel. These two wheels rotate at varying speeds in the same direction, and they determine the rate of metal removal from an object. 

It is more similar to centerless grinding; no chuck or spindle holds the workpiece, the work rest blade will always balance it. Cylindrical grinding machines are familiar in applications that require precision engineering. It works by shaping the outside of a workpiece, rotating it, and grinding around a central axis.

Adjusting CNC grinder speed

Always disconnect the grinder from power before adjusting speed.

You can change the motor’s rotational velocity by voltage resistance or frequency control. Generally, a grinder comes with specific speed regulations, and adjusting other parts of the machine to suit your speed levels can damage the device. Always refer to the manufacturer manual for speed adjustments.  

How to use your CNC grinder

Use your CNC grinding machine when you want to cut away excess material from your metal workpiece using a high-speed abrasive wheel.

The wheel rotates in place while your workpiece attached to the working table moves in the X, Y and Z-axis. An operator should feed the grinder machine with commands or instructions to perform the task. The device then uses the instructions to slowly move its grinding head onto the workpiece.

Placing the bit on the spindle

The bit should be entirely through the spindle so that it gets a grip. If you put it in too far, the spindle cannot pull down on it properly to tighten or score the bit.

Setting up the table height

The table height should be sizable enough to allow the bit to reach down to the desired drilling depth. The bit should not contact the table, and the supporting bracket must be in place.

Setting up the spindle speed

It will help if you consider the following when setting the spindle speed

  • The size of the bit
  • The type of cutter
  • Type of material
  • Feed rate

You can use a higher spindle speed for small cutters and soft materials.

Always refer to the guidelines from the cutting tool manufacturer for setting the optimum speed.

Setting up the feed speed

Control the feed rate to avoid overheating. The optimal feed rate depends on the bits and the material type. It is always best to keep the feed rate consistent.

David D. Hughes
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