Surface Grinding Report

TITLE: UNIVERSAL SURFACE GRINDING

INTRODUCTION Surface grinding is used to produce a smooth finish on flat surfaces. It is a widely used abrasive machining process in which a spinning wheel covered in rough particles (grinding wheel) cuts chips of metallic or non-metallic substance from a work piece, making a face of it flat or smooth.

Surface grinding is the most common of the grinding operations. It is a finishing process that uses a rotating abrasive wheel to smooth the flat surface of metallic or non-metallic materials to give them a more refined look or to attain a desired surface for a functional purpose. The surface grinder is composed of an abrasive wheel, a work holding device known as a chuck, and a reciprocating or rotary table. The chuck holds the material in place while it is being worked on. It can do this one of two ways: ferromagnetic pieces are held in place by a magnetic chuck, while non-ferromagnetic and non-metallic pieces are held in place by vacuum or mechanical means. A machine vies (made from ferromagnetic steel or cast iron) placed on the magnetic chuck can be used to hold non-ferromagnetic work pieces if only a magnetic chuck is available. Factors to consider in surface grinding are the material of the grinding wheel and the material of the piece being worked on. Typical work piece materials include cast iron and mild steel. These two materials don't tend to clog the grinding wheel while being processed. Other materials are aluminium, 1

stainless steel, brass and some plastics. When grinding at high temperatures, the material tends to become weakened and is more inclined to corrode. This can also result in a loss of magnetism in materials where this is applicable. The grinding wheel is not limited to a cylindrical shape and can have a myriad of options that are useful in transferring different geometries to the object being worked on. Straight wheels can be dressed by the operator to produce custom geometries. When surface grinding an object, one must keep in mind that the shape of the wheel will be transferred to the material of the object like a mirror image. Spark out is a term used when precision values are sought and literally means "until the sparks are out (no more)". It involves passing the work piece under the wheel, without resetting the depth of cut, more than once and generally multiple times. This ensures that any inconsistencies in the machine or work piece are eliminated.

TYPES OF SURFACE GRINDERS 1. Horizontal-spindle (peripheral) surface grinders. 2. Vertical-spindle (wheel-face) grinders. 3. Disc grinders and double-disc grinders.

THE BENEFITS OF SURFACE GRINDING ARE • You can grind very hard or abrasive materials • High degree of dimensional accuracy • Produces surface textures of very high finish • Tooling is less expensive • Work holding is easier because of magnetic chuck • Can be done automatically

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1. Horizontal-spindle (peripheral) surface

Grinders.

The periphery (flat edge) of the wheel is in contact with the work piece, producing the flat surface. Peripheral grinding is used in high-precision work on simple flat surfaces; tapers or angled surfaces; slots; flat surfaces next to shoulders; recessed surfaces; and profiles.

2. Vertical-spindle (wheel-face) grinders

The face of a wheel (cup, cylinder, disc, or segmental wheel) is used on the flat surface. Wheel-face grinding is often used for fast material removal, but some machines can accomplish high-precision work. The work piece is held on a reciprocating table, which can be varied according to the task, or a rotary-table machine, with continuous or indexed

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rotation. Indexing allows loading or unloading one station while grinding operations are being performed on another.

3. Disc grinders and double-disc grinders

Disc grinding is similar to surface grinding, but with a larger contact area between disc and work piece. Disc grinders are available in both vertical and horizontal spindle types. Double disc grinders work both sides of a work piece simultaneously. Disc grinders are capable of achieving especially fine tolerances. Aluminium oxide, silicon carbide, diamond, and cubic boron nitride (CBN) are four commonly used abrasive materials for the surface of the grinding wheels. Of these materials, aluminium oxide is the most common. Because of cost, diamond and CBN grinding wheels are generally made with a core of less expensive material surrounded by a layer of diamond or CBN. Diamond and CBN wheels are very hard and are capable of economically grinding materials, such as ceramics and carbides, that cannot be ground by aluminium oxide or silicon carbide wheels. As with any grinding operation, the condition of the wheel is extremely important. Grinding dressers are used to maintain the condition of the wheel, these may be table mounted or mounted in the wheel head where they can be readily applied.

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OBJECTIVE 1. Know how to grind the surface of a metal object. 2. Know about the function of the universal surface grinding machine. 3. Understand the functioned the type of tools used in the universal surface grinding machine. 4. Knowing method about how the work

SAFETY PRECAUTION 1. Wear a goggle before start the works. 2. Wear safety shoes. 3. Avoid wear jewellery while using this surface grinding machine. 4. Make sure the machine is safe before use. 5. Use appropriate machine speed. 6. Switching off the machine after use. 7. Make sure the machine is used with safety switch and another switch lock.

SAFETY PRECAUTIONS DURING RUN MACHINE •

Wear appropriate safety glasses. In addition, use the eye shield on the grinder, when provided.

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Ensure that the grinder has a start/stop button within easy reach of the operator.

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Check the grinding wheel before mounting it. Make sure it is properly maintained and in good working order.

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Follow the manufacturer's instructions for mounting grinding wheels.

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Keep face of the wheel evenly dressed.

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Ensure that the wheel guard covers at least one half of the grinding wheel.

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File off any burrs on the surface of work that is placed on the magnetic chuck.

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Clean the magnetic chuck with a cloth and then wipe with the palm of your hand. 5

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Place a piece of paper slightly larger than workpiece in the centre of chuck.

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Position work on the paper and turn on the power to the magnetic chuck.

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Check that the magnetic chuck has been turned on by trying to remove work from the chuck.

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Check that the wheel clears the work before starting the grinder.

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Run a new grinding wheel for about one minute before engaging the wheel into the work.

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Stand to one side of the wheel before starting the grinder.

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Turn off coolant before stopping the wheel to avoid creating an out-of-balance condition.

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Keep the working surface clear of scraps, tools and materials.

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Keep the floor around the grinder clean and free of oil and grease.

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Universal

surface

grinding

machine -

Used

to

produce

the

smooth finish and flat surface of the work piece.

VernierCalliper -

Used

to

measure

the

diameter and the length of work piece.

Goggle -

To protect the eyes from dust, including iron.

PROCEDURE: 1. Surface grinding machine was started 2. The speed, angle of rotation, height of table and etc has been setting. 3. The work piece has been clamp tightly to avoid it flew away. 4. The movement of the magnetize table was set. 5. The machine started to feed the work piece. 6. The grinded shouldn’t very big or else the work piece will be damaged. 7. Make sure the surface object doesn’t had any rust strain after it has been grinded

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EQUIPMENT A surface grinder is a machine tool used to provide precision ground surfaces, either to a critical size or for the surface finish. The typical precision of a surface grinder depends on the type and usage, however +/0.002 mm (+/- 0.0001") should be achievable on most surface grinders. The machine consists of a table that traverses both longitudinally and across the face of the wheel. The longitudinal feed is usually powered by hydraulics, as may the cross feed, however any mixture of hand, electrical or hydraulic may be used depending on the ultimate usage of the machine (i.e.: production, workshop, cost). The grinding wheel rotates in the spindle head and is also adjustable for height, by any of the methods described previously. Modern surface grinders are semi-automated, depth of cut and spark-out may be preset as to the number of passes and, once set up, the machining process requires very little operator intervention. Depending on the workpiece material, the work is generally held by the use of a magnetic chuck. This may be either an electromagnetic chuck, or a manually operated, permanent magnet type chuck; both types are shown in the first image. The machine has provision for the application of coolant as well as the extraction of metal dust (metal and grinding particles).

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PROCEDURE FOR USE SURFACE GRINDER

The first step in using the surface grinder, is to make sure that the material you wish to shape can be used in the grinder. Soft materials such as aluminum or brass will clop up the abrasive wheel and stop it from performing effectively, and it will then have to be cleaned. This process is explained in the Maintenance section. The maximum size of a material that the grinder can machine is 18” long by 8” wide by 6” high. The next step is to make sure the material is secured. This is done by use of a vice, and then by engaging the magnetic clamp. Once the material is secure, it must be manually positioned under the abrasive wheel. This is done by turning the longitude and latitude wheels located on the front of the grinder. The abrasive wheel itself can be moved slightly to get the material in the perfect position. Then the machine may be started. It should reach maximum speed before you try to use it for the safety reasons mentioned before. If the wheel is working properly, then the hydraulic table can be activated which will then begin to oscillate under the wheel, cross-feeding towards or away from you as required. The automated speed and direction of the table’s oscillations can be set as required, or manually used when very precise work needs to be done. If needed, a lubricant may be used to speed up or facilitate the grinding process. For this machine “Cutwell 45” is used. It is delivered via a tube beside the wheel, and falls onto the material being used. The excess fluid is then drained into the reservoir.

CLEANING

A wire wheel mounted to a utility grinding machine is used for cleaning operations such as removing rust, paint, or dirt from metal objects. If the utility grinding machine on which the wire wheel is to be mounted is equipped with wheel guards and tool rests, these parts should be removed or swung out of the way so that the objects to be cleaned can be brought against the wheel without interference. To clean objects with a wire wheel, place the object firmly against the wire wheel. Work the object back and forth across the face of the wheel until all traces of rust, paint, or 9

dirt are removed. Avoid excessive pressure against the face of the wire wheel to prevent spreading the steel wires. Keep the point of contact below the center of the wheel to avoid kickback of the workpiece.

LUBRICATION Lubricants are sometimes used to cool the workpiece and wheel, lubricate the interface, and remove swarf (chips). It must be applied directly to the cutting area to ensure that the fluid is not carried away by the grinding wheel. Common lubricants include watersoluble chemical fluids, water soluble oils, synthetic oils, and petroleum-based oils. The type of lubrication used depends on the workpiece material and is outlined in the table below. Types of lubricants used for grinding based on workpiece material Workpiece material Aluminium

Lubricant

heavy duty oil

Brass Light duty oil Cast iron

Heavy duty emulsifiable oil, light duty chemical and synthetic oil

Mild steel

Heavy duty water-soluble oil

Stainless steel Heavy duty emulsifiable oil, heavy duty chemical and synthetic oil Plastics

Water-soluble oil, dry, heavy duty emulsifiable oil, light duty chemical and

synthetic oil

EFFECTS ON WORK MATERIAL PORPERTIES The high temperatures encountered at the ground surface create residual stresses and a thin martensitic layer may form on the part surface; this decreases the fatigue strength. In ferromagnetic materials, if the temperature of the surface is raised beyond the Curie temperature then it may lose some magnetic properties. Finally, the surface may be more susceptible to corrosion.

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THINGS YOU SHOULD AVOID DOING •

Do not run a grinding wheel faster than the speed recommended on the wheel.

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Do not clean the magnetic chuck or mount or remove work until the wheel has completely stopped.

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Do not grind material for which wheel is not designed.

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Do not grind without proper ventilation.

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Do not start the machine until the wheel guard is in place.

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Do not stand directly in front of a grinding wheel when starting a grinder.

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Do not apply work too quickly to a cold wheel or disk.

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Do not jam work into the wheel.

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Do not reach above or around a moving wheel.

EXAMPLES OF FINISHED PRODUCT OF SURFACE GRINDER

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DISCUSSION Surface finish is an important index of machinability or grind ability because the performance and the service life of the ground component are often affected by its surface finish, nature and extent of residual stresses and presence of superficial or sub superficial micro cracks. The roughness of a ground component is mainly influenced by size of abrasive grain, dressing conditions, feed rate, spark-out time and cooling conditions. The analysis of the results obtained with the conventional cutting fluid application system and with the MQL technique indicates that the application of cutting fluid by MQL technique led to satisfactory results in comparison to the conventional system, due to the more efficient penetration of the fluid into the cutting region.

CONCLUSION Surface grinding is an abrasive machining process in which the grinding wheel removes material from the plain flat surfaces of the work piece. In surface grinding, the spindle position is either horizontal or vertical, and the relative motion of the work piece is achieved either by reciprocating the work piece past the wheel or by rotating it.

REFERENCES Tool and Manufacturing Engineers Handbook (TMEH), 4th edition, Volume 1, Machining. Society of Manufacturing Engineers, 1983 Todd, Robert H.; Allen, Dell K.; Alting, Leo (1994), Manufacturing Processes Reference Guide.

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