Surface Grinder In-depth Introduction & Guide

Posted on Sep 26, 2020

Surface Grinder

A surface grinder is a type of grinder mainly used for finishing processes. It utilizes an abrasive, rotating wheel to finish the surface of a workpiece which is held in place by a vise. Aside from finishing, surface grinders can also cut a variety of metal into smaller pieces.

A surface grinder is mainly used for finishing processes. It utilizes an abrasive, rotating wheel to finish the surface of a workpiece which is held in place by a vise. Aside from finishing, surface grinding machines can also cut a variety of metal into smaller pieces.these machine tools are sure to meet the manufacturing requirements. Read on for a more in-depth introduction to this piece of amazing grinding equipment.

The Basics

A surface grinder is one of the most common grinder machine tyopes. It can grind different types of metals and non-metals that require a refined and smooth surface. So what makes surface grinding so popular? When processing a part with other machining operations such as milling or turning, part tolerances and surface quality deteriorate as the tool inserts wear. However, the abrasive wheel can be dressed to maintain the sharp cutting edges, resulting in consistent finishing and high dimensional accuracy. Check out the blog entry below to find out who uses these surface grinders:
 

→ Read More: CNC Grinding Machines - Practical Machines
 

The main purpose of surface grinding machines is the finishing of a manufactured part. This is a very precise tool that uses a fixed, abrasive rotating wheel to shave or trim a metal surface held in place with a vise. The table of the grinder is magnetic, which helps to keep the material stationary. Such magnets can be switched by the lever on the front side of the grinder. The grinder can be moved automatically, back and forth, or manually as needed.

Surface grinding is a common finishing technique that can produce smooth surface textures precisely. The surface finish is both beautiful and practical, making it a reliable technology for different applications. Technicians may also change the form of wheel and abrasive to match a range of materials, including most metals and non-metals, such as ceramics, carbides and optical materials. Unlike other molding methods, it can be ground on extremely hard or abrasive materials.

Furthermore, surface grinding today is often coupled with a CNC system for more precision and efficiency. The following video is a demonstration of the high-end, CNC surface grinder by Equiptop:


 

Construction and Key Components

The structural design of a surface grinder is simple. The main parts include a worktable, a grinding wheel, a power system, and a frame. The frame pulls all the necessary components and auxiliary equipment together. Depending on the final application, there may be attachments to assist the process.

Worktable

The worktable is the working surface of the grinder. It is where the workpiece is placed and the grinding process is performed. On the worktable, a fixture, or a work-holding device, is installed to hold the workpiece in place during operation. The common work holding devices include chucks and vises. The table moves horizontally during the grinding process, as the grinding wheel grinds away fractions of the workpiece.

The table advances linearly and also across the face of the abrasive wheel during the precision surface grinding operations. The longitudinal feed is generally powered by a hydraulic system, on the other hand, the crossfeed is often driven by an electric, hydraulic system, or even regulated manually.


Grinding Wheel

The grinding wheel is the cutting tool of the grinder. It is an abrasive disc that contains grit also referred to as grains. The grains serve as the cutting edges that cut the workpiece. The size and material of the grits determine the application of the grinding wheel. The smaller the grits, the finer and smoother the surface. Besides the grit size, the feed rate and the rotating speed also affect the use of the machine.

The grinding wheel is one of the most important components in a precision surface grinder. The round wheel rotates in the spindle head, and the height of it can be adjusted to meet the operational requirements. The condition, as well as the material the grinding wheel is made from, is essential to affect the performance of precision grinders. In general, the abrasive wheel is made from aluminum oxide, cubic boron, silicon carbide, and diamond. The most economic one among them, aluminum oxide, is the most preferred grinding wheel material.

To reduce the cost but enhance the functionality, many manufacturers use less expensive alternatives in the core of cubic boron nitride wheel and diamond grinding wheel. The grinding wheel which is made from diamond or cubic boron nitride is ideally strong, which is better suited for grinding ceramics, carbides, and more tough materials that are typically difficult for other kinds of an abrasive wheel. To always maintain the best condition of the grinding wheels, dressers are used to refresh the surface of the component and the balancing stands are used to detect and improve the imbalances relative to the tolerance, the parallelism, the concentricity, as well as the wear of the grinding wheel.


Figure 1. Surface Grinder Components
 
Power System

In the past, a grinding machine was operated manually by the machinist. The machinist had to constantly turn the grinding wheel on and off with a shank or a screw. This limits the quality, efficiency, and precision of the grinding. Today, high-precision surface grinders for heavy-duty projects are used in order to offer a sustainable power output and speed. The electric rotary motor is used as the power source for most CNC grinders today.

Controller

To automatically produce highly accurate and efficient surface grinding, many precision surface grinders employ a CNC system to fully regulate the desired depth of the cut and the sparks. The values are predetermined and set up simply. In addition, the last grinding cycle setting can be saved and repeated simply next time. With the servo control, the grinder can provide products with excellent, smooth surface finishes and critical dimensions.

Chuck

The chuck is the work-holding device that grips the ground parts firmly. In precision surface grinders, a magnetic chuck is widely used. The clamping device can be electromagnetic, or a permanent form that needs to be manually operated.

Coolant and Lubricants

Lubricants are required in operations of precision surface grinder, which can not only smoothen the cutting and face of the grinding wheel but remove the metal chips formed during operations. In some cases, lubrication can also cool down the working wheel as well as the workpieces. The lubricants are mostly directly applied to the grinding area to keep the liquid from carrying away by the rotation of the component. Some common lubricants working with a precision surface grinding machines include water-soluble oils, petroleum-based oils, synthetic oils, and other chemical fluids.

Surface Grinder Types

There are three basic types: horizontal, vertical, and disc grinders. The main difference lies in how the grinding wheel makes contact with the workpiece.

The wheels of the horizontal spindle design are suspended above the worktable. Only the flat outer edge of the wheel will come into contact with the object held by the chuck. Thanks to the small grinding surface, you can have high precision every time you cut, which is why they are usually used when small features are required. Like there are two common types of spindles, there are also two common types, both of which only grind flat surfaces.


● Horizontal Spindle 

This type of surface grinder is the most common in the industry. It is best suited for high-precision work, such as angular or conical surfaces, grooves, or recesses. Pins, pistons, connecting rods, and bearing races are examples of parts ground with this type of machine.



● Vertical Spindle 

Vertical spindle grinders are usually used for rapid material removal. The most noticeable difference is that the face of the grinding wheel is used on the flat surface instead of the edge. Vertical spindle grinders are ideal for grinding stators, plates, rotors, gears, inner rings and plates, and stops and spacers.

These machines and are arranged so that the flat edge of the grinding wheel is in touch with the workpiece. This results in flat shape with a smooth surface. Thanks to this configuration, these machines can be used for applications that require a flat surface, although these include the precise forming of diagonals, grooves, and grooves. The vertical spindle design has the spindle vertically up and down. The grinding wheel itself lies flat on the bottom of the spindle, so the entire width of the grinding wheel can be used for grinding objects. Generally, this design is used in situations that require processing on larger panels or plates or where a large amount of material needs to be quickly ground.

● Single-Disc and Double-Disc

Single-disc and double-disc grinders can be incorporated in both horizontal-spindle and vertical-spindle models. Disc grinders have a larger contact area between the grinding surface and the workpiece and can grind both sides at once. Components such as rotors, plates, spacers, gears, and washers are all ideal candidates for disc grinders.


 

Operation and Functioning Principle

When powered on, the grinding wheel spins at high speed. Once the workpiece is secured at the desired height, the spinning wheel is positioned just above the workpiece. The table will then begin to move from side to side, as the work bed elevates slightly for the grinding wheel to come in contact with the workpiece. The working bed also moves in and out, which allows a more even grinding of the workpiece.

It is worth noting that the grinding wheel doesn't have to be completely straight during the process. In certain applications where a specific pattern on the surface of the ground part is required, you may adopt a wheel with custom profiles to achieve that pattern. Alternatively, you can simply machine a pattern into a straight grinding wheel to attain the same effect.

Check out the video below as it illustrates the movement of the grinding wheel and worktable:


(Copyright@To Know Everything, YouTube)
 

Applications

The main industries that make use of surface grinders are outlined as follows:

● Aircraft
The aerospace industry is known for machining materials that are difficult to machine using conventional tools. These tough, high-temperature resistant materials allow the components to perform under harsh conditions of aircraft engines. Turbine rings, turbine shafts, and inner and outer rings are all some of the more common aircraft components that are precisely ground.

● Machine Tool 
Surface grinders are often found in the machine tool industry as well. Machine tool builders use them to make main shafts, linear guides, ball screws, indexers, roller bearings, cams, racks, valve cores, and more.

● Mold & Die
The mold industry uses surface grinders to produce thread dies, stamping dies, bending machines, wire drawing dies, rolling dies and inserts, and many other mold components.

Other tools that are produced with high-precision grinders include three- and four-jaw chucks, shaped blades, step drills, drill taps, reamers, taps, and ring gauges. Tool holders are also another category that frequently utilizes surface grinding.
 

Boosting Surface Grinder Performance

Finally, we want to share with you some tips on how to get the most out of your surface grinder:

Installation and Initial Maintenance

Grind the machine table flat and deep enough to remove all rust. The bottom of the electromagnetic chuck is also ground, so there are approximately 0.00002-inch dishes for every 6-inch chuck length. Then apply a thin layer of oil between the surfaces between the chucks, and tighten the right-hand bolt first, and then press the left-hand bolt tightly. The chassis has only one side bolt, which can make the chuck move due to thermal changes while minimizing flatness.

Scheduled Maintenace of Grinding Wheel

These steps are completed in our workshop every year because of the accumulation of rust between the chuck and the machine bed of a surface grinder. Selection and balance of grinding wheel Choose a grinding wheel that does not introduce pressure or heat into the workpiece. Your wheel supplier should be able to help you choose the right wheel. Grinding wheel balance is an important part of surface grinding. A grinding wheel that is not balanced properly causes poor surface finish and shortens the life of the bearing spindle.

During the lifetime of the grinding wheel and the machine as a whole, the balance of the molding wheel should be checked because the diameter decreases, and the balance of the molding wheel changes. Based on our experience, the smallest diamond size should be half a carat per inch of the wheel surface. The big diamond has a better heat dissipation effect, longer service life, and because of more contact with the grinding wheel, the dressing speed is also faster. The diamond should be set approximately to ten degrees in the direction of the wheel position. Minimize the length of the handle and install it as firmly as possible. If possible, use a lot of coolants. Rotate the diamond to a sharp surface as much as possible to ensure the best performance of your surface grinder.

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