Metal Grinding and Polishing
Grinding entails using bonded abrasives in wearing away parts of metal workpieces. The goal is giving your workpiece a particular shape, increase the surface smoothness, correct the dimensions, and enhance the cutting edges’ sharpness. Examples are removing rough edges and sprues from foundry castings, removing surface scales from the metal before you weld or forge and deburring sheet metal parts and machine shops.
Polishing is utilized in the removal of surface imperfections like the tool marks. Buffing doesn’t remove metals but utilizes soft abrasives that is blended with a grease or wax base to create a high-lustre surface. One of the companies that specialize in metal griding and polishing is Aluminum Welding. We offer our services to the residents of Ventura, Riverside, San Bernardino, Los Angeles, and Orange County. Feel free to come to us for metal grinding and polishing if you reside in any of the cities within these locations.
Grinding remains as the most diversified and comprehensive machining technique and you can employ on different types of metals. The most predominant ones are steel and iron even though you can use it on all metals. The technology also covers the other methods that are used to produce glossy and smooth surfaces like lapping, whetting, honing, and polishing.
Welders use wheels that have varying discs, belts, polishing wheels, files, sharpening stones, grinding points, dimensions etc. to carry out this process. In cases like the grinding wheels, bonding agents hold together the abrasive material to form a rigid and porous body. In the instance of abrasive belts, the bonding agent is used to hold the abrasive that is secured to a highly flexible base material. The buffing wheels are created from textile disks like cotton that are sewn together.
Natural abrasives, aluminum oxides (emery) or natural corundum, sandstone, diamond, garnet and flint have been superseded by artificial abrasives largely including fused alumina (aluminum oxide), synthetic diamonds, and carborundum (silicon carbide). Several fine-grained materials like Tripoli, pumice, chalk, iron oxide, and Tripoli are utilized especially for buffing and polishing.
Aluminum oxide is broadly utilized in grinding silicon carbide and wheels. Experts use artificial and natural diamonds for the special applications. Flint, garnet, emery, silicon carbide, and aluminum oxide are utilized in polishing and grinding belts. All these are the things that we do in our company on a daily basis.
Both inorganic and organic bonding agents are used to grind wheels. Magnesite and vitrified silicate are the major forms of inorganic bonds. Among the bonding agents, the most notable ones include urea or phenol, shellac, rubber, and formaldehyde resin. The phenolic resin and vitrified bonding agents are dominating completely in their respective groups. You can also metal bond the diamond grinding wheels. The different bonding agents provide the wheels with various grinding properties together with varying properties regarding safely.
Polishing and abrasive discs and belts comprises flexible base fabric or paper that bonds the abrasive by means of synthetic or natural adhesive. Different machineries are applied for different kinds of operations like cutting, rough grinding, internal grinding, cylindrical grinding including centerless, and surface grinding. The two major types are the ones in which either the work or the grinder is moves by machines or hand with chucks and mechanical feeds. The common types of equipment are multiple buffers and polishers, portable grinders, belt polishers, abrasive cut-off machines, internal grinders, disk polishers and grinders, duffers and polishers, pedestal-type grinders, and surface-type grinders. All these machines are available in our aluminum welding website for daily assignments.
How to Prevent Hazards
The main injury risk in using grinding wheels is that the wheel can burst in the process of grinding. In most cases, grinding wills operate under very high speeds. The speed tends to be ever-increasing all the time. Most of the industrialized countries have regulations that limit the maximum speed at which the different kinds of grinding wheels can run. The recommended speed virtually depends on the type of grinding machine that you are using.
The basic measure of protection is making the grinding wheel to be very strong. It is also important to pay close attention to the nature of the bonding agent. Wheels that have organic bonds, phenolic resin to be precise, are tougher than the ones that the ones that have inorganic bonds and are also more resistant to impacts. Higher peripheral speeds could be permissible for wheels that have organic bonds.
Wheels that have very high speeds use different types of reinforcements. For instance, some cup wheels have stub hub fittings to enhance their strength. Most of the stress develops around the central hole during rotation. To strengthen the wheel, you need to make the section around the wheel from very strong materials that is not ideal for grinding as this section has no role to play in the grinding. Large wheels that have a central section reinforced in this manner are utilized specifically by steel works in grinding materials like billets, and slabs at speeds that are as high as 80 m/s.
However, the most common technique of reinforcing wheels is including the glass fiber fabric in their construction. The thin wheels like the ones that are utilized in cutting may have a glass fiber fabric at their center or at every side and the thick wheels have several fabric layers depending on the wheel’s thickness.
With the exemption of some grinding wheels that have a small dimension, the manufacturer has to give speed tests to either a statistical sampling of the wheels or all of them. While testing, they run the wheels over a given period at a speed that exceeds what is permitted in grinding.
The testing regulations differ from one country to another. However, the wheel should be tested at a speed that is 50% higher than its normal working speed. In some nations, regulations call for special testing of wheels that need to operate at very high speeds than normal and this should be done at a central testing institution. The institute can also cut the required specimen from the wheel to help them investigate their physical properties. They subject the cutting wheels to some form of bending tests, impact testing, and so on. The manufacturer should also make sure that he balances the grinding wheel well before the delivery. The bursting of a grinding wheel can cause very serious or fatal injuries to those who are in the vicinity and even heavy damages to the premises or plant. Despite all the precautions that the manufacturers have put in place, occasional wheel breaks or bursts still take place unless you exercise proper care on how you use them. These precautionary measures include;
Storing and Handling
A wheel can become cracked or damaged during handling or transit. Moisture can attack the bonding agent that is in the phenolic resin wheels hence reducing their strength. The vitrified wheels can be sensitive to repetitive variations in temperature. Moisture that is absorbed irregularly may course imbalance to the wheels. Subsequently, you need to handle the wheels with a lot of care at all the stages and store them in an orderly manner in a place that is protected and safe.
Checking for Cracks
You need to check the new wheels and make sure that it is dry and undamaged. The most common approach is using a wooden mallet to tap it. A vitrified wheel that is faultless yields out a clear ring, a less ringing tone for an organic bonded wheel, and you can differentiate either of them from the cracking sound in a defective wheel. If there are doubts, make sure you don’t use the wheel and you also need to consult the supplier with immediate effect.
Before you put the new wheel into service, you need to test it at full speed because of the precautions that you are observing. After wet grinding, run the wheel idle in order to eject that water. Failure to do this, the water may gather at the bottom of the wheel and lead to an imbalance and this may make the wheel to burst when you use it the next time.
If you mount the grinding wheels on unsuitable apparatus, it can lead to breakages and accidents. Some examples would be the spindle ends of the buffing machines. The spindle should have enough diameter but not too large to expand the central hole of the wheel. The flanges should not be lower than one third of the wheel diameter and created from mild steel or other similar materials.
You should never exceed the maximum permissible operating speed that the manufacturer has specified. Make sure you fit a notice that indicates the speed of the spindle on all the grinding machines. Besides, mark the wheel with the maximum peripheral speed that is permissible and the corresponding sum of revolutions for the new wheels. You need to take special precautions with various speed grinding machines to make sure that the fitting of wheels that have permissible speeds in the portable grinders.
When possible, you need to provide rigidly mounted work rests that have enough dimensions. You need to adjust them and keep them as close as possible to the grinding wheel to avoid a trap that may force the work against the wheel and also break it as this may injure or catch the hand of the operator.
You should provide the abrasive wheels with the guards that are strong enough to be able to contain the sections of your bursting wheel. In some states, there are detailed regulations about the materials that you should use and the design of the guards. Generally speaking, you should avoid cast aluminum and cast iron by all means. Keep the opening of the grinding as small as you can and there may be need to have an adjustable nose piece. When the nature if the task does not allow you to use a guard, you can go for safety chucks or special protective flanges. The tapered ends and spindles of the double-ended polishing machines can result into entanglement accidents unless you are able to guard them effectively.
The most common hazards to your eyes during all the dry-grinding operations include splinters, grains, abrasives, and dust. Fixed eye shields and spectacles or goggles provide an effective protection to the eyes when using the machine. If you are using the grinding wheels in the intermittent form like in tool grinding, fixed eye shields come in handy.
Magnesium allow grinding comes with a very high risk unless you take strict precautions against the accidental ignitions and during the drenching and removal of dust. You need to maintain very high standards of cleanliness in the exhaust ducting in order to prevent the fire risk and also make sure that the ventilation works effectively. The textile dust that is released from the buffing operations is another fire hazard that calls for good LEV and housekeeping.
Pedestal and portable grinders come with the hand-arm vibration syndrome risk (HAVS). It is also referred to as the ‘white finger’ from the most noticeable sign. Recommendation are that you limit the duration of exposure and intensity, redesigning tools, monitoring exposure, protective equipment and health.
The modern grinding wheels don’t create serious silicosis hazards by themselves. The past sandstone wheels are associated with dangerous silica dust. It can still give off these particles from the materials that you are grinding like sand castings.
Some resin-bonded wheels may have fillers that create dangerous dust. To add on this, formaldehyde-based resins could emit formaldehyde while grinding. The dust volume that is produced when grinding makes effective LEV important. Providing local exhaust for portable wheels is harder even though we have reported some success in this direction by using low volume and high velocity capture systems. Avoid prolonged work and also wear protective equipment when necessary.
Operations such as polishing, finishing, and belt sanding among others also require exhaust ventilation. In buffing, to be particular, there is a serious concern of combustible textile dust. Good washing and sanitary facilities that have showers and protective clothing may be provides and there is also a need for medical supervision. These requirements are specifically crucial when dealing with metal grinders.
If you are looking for the best metal grinding and polishing professionals, all you need to do is come to our Aluminum Welding Company. We offer our services in Ventura, San Bernardino, Riverside, Los Angeles and Orange County. You can be sure of getting high quality low price metal grinding and polishing services.
From our offices in California, Aluminum Welding serves households and businesses in Ventura, Riverside, San Bernardino, Los Angeles and Orange County. We offer a broad range of metal fabrication services to our esteemed customers. Contact us today to learn the kind of services that you can get from us.