Troubleshooting 4 Common Problems in Metal Cutting
By Jeff Hauke, district sales manager, Weiler Abrasives
When cutting metal, it’s not uncommon to encounter problems that can negatively affect your efficiency and results — and pose safety hazards for workers. From short product life to wheel damage or product failure, these challenges can be costly.
Learn how to identify and solve issues when using cutting wheels so you can get the most out of your cutting products and optimize results.
Issue No. 1: Short wheel life
Short cutting wheel life can occur for a number of reasons, including excessive pressure, an underpowered or overpowered tool, too soft of a grain for the application, and more. Consider these common causes and their solutions:
- Excessive pressure: Too much pressure heats up the wheel, causing it to break down much faster and can weaken its structure. Instead, cut with less downward pressure and incorporate motion through the cut. Moderate pressure that lets the wheel do the work will result in much faster and better cutting action. Not to mention that it’s safer.
- An underpowered tool Ceramic grains require tool speed to fracture and an underpowered tool doesn’t have the power to break down the grain, which reduces the grain’s ability to maintain sharpness. The more torque your cutting tool has, the more power available to fracture the grains so they can do the work. Choose a higher-powered tool to maximize performance when choosing a ceramic product.
One factor that is commonly overlooked is to use a power cord that is at no less than 12 gauge and 10-gauge is preferable. Power and extension cords designed for home use can “choke” power to the grinder and lead to significant power loss.
- Ignoring shelf life: The abrasive that holds the wheel together has a shelf life and will start to degrade after that time. While the wheel is still safe to use, performance won’t be as good. Replace the wheel before it hits the three-year mark after its manufacturing date. Keep stock levels low enough that the product doesn’t get too old and rotate older products to the front of your stock so they get used.
- Inappropriate storage: Extreme temperature changes affect the bond. Be sure to store wheels in a clean, dry location with a consistent temperature. Always store product on a flat, stable surface to minimize the potential for warping and cracking.
- The wrong product bond: Match the bond of your product to the material you’re cutting. Softer bonds (N, R) will cut faster, but also break down faster, reducing life. Harder bonds (S, T) will last longer but can be more difficult to control. Inexperienced operators may notice higher vibration and reduction in cut speed. A good general rule: The harder the metal, the softer the bond you want to use, and vice versa.
Issue No. 2: Edge glazing
Glazing and loading occur during cutting when the base material heats up and adheres to the cutting wheel. Common causes include:
- Product that’s too hard: You want the product bond to break down, shedding dulled grains and replacing them with fresh, sharp grain. This allows the wheel to continue to cut efficiently. If the product bond is too hard, the dull grains remain, which causes heat to build up and glazing can occur. If you are frustrated by glazing, choose a softer bond, which will break down with less pressure and cut more efficiently with the fractured grains.
- Not enough motion through the cut: In an offhand application with a cutoff wheel, use consistent movement and effective pressure for cutting. A rocking motion through the cut — going forward and back on an even keel — provides a better cut and reduces heat and friction that can cause glazing.
- Insufficient pressure: Not using enough pressure can cause the wheel to skip and chatter rather than bite and cut. Again, a rocking motion and even, consistent pressure through the cut helps.
Issue No. 3: Flange or arbor hole damage
Always inspect cutting wheels for damage before using them. Damage to the flange or arbor hole can weaken the wheel and lead to product failure — and pose a safety risk. Damage to the flange or arbor hole can be caused by:
- Excessive pressure: This can happen when you’re using a cutting wheel that’s too thin for the job. If you feel yourself needing to apply too much pressure and it’s causing damage to the wheel, switch to a thicker wheel.
- Excessive side load: A cutting wheel is designed to cut on its edge, so there is no extra fiberglass reinforcement to support side grinding. If the operator tries to use the side of the wheel, similar to how they would use a grinding wheel, it damages the fiberglass reinforcement keeping the wheel together. Once a defect starts in the wheel, it will continue to grow and create cracks and the wheel can fail. To prevent this, use a product with two layers of fiberglass and maintain a 90-degree angle to the workpiece during the cut.
- Workpiece not properly clamped: When the base material isn’t properly clamped, it can create vibration, which can lead to loss of wheel control, binding and structural damage to the wheel. Properly clamping the workpiece keeps it firm and steady while you’re cutting. It also allows you to maintain the 90-degree angle and use a slight rocking motion.
- Product binding and vibration: When using any cutting wheel, it is important to maintain a consistent, straight line. Twisting or bending a wheel during a cut or attempting to cut rounded corners or arcs can cause the wheel to bind and potentially break. Binding can also cause a wheel to kick back towards the operator. If a wheel does bind or stop during a cut, never attempt to restart the wheel while it is in the cut line. Remove the wheel and check for damage. Start the wheel away from the workpiece and allow the wheel to come to full speed before re-entering the cut line. Never try to correct or re-straighten a crooked cut. It is safer and more efficient to remark a new line. Twisting a wheel to get it “back on course” creates an unsafe condition and will cause the wheel to bind.
- Improper Mounting: Take care not to over-tighten a cutting wheel when installing. Over-tightening can damage the arbor hole and create a stress-riser during cutting. Adapting nuts come in different diameters, but it’s also very important to use adapting nuts with the same diameter to help prevent wheel damage. Using different diameters can cause the wheel to “cup,” making the wheel unbalanced and difficult to control.
Issue No. 4: Damaged edges
As previously stated, the wheel should always be properly inspected before every use — whether it’s a new wheel or a wheel already on the tool. Small cracks and damage can be difficult to see. To check a wheel for damage, turn the tool on to jog it for about a minute while holding it away from your face and body to see if there is any vibration, unbalance, or chunking which will typically happen if there is edge damage. If the wheel is out of round, it’s likely damaged.
Cutting tools run extremely fast, and even a small crack on the edge can spread and cause the wheel to break apart. The edge of a cutting wheel should never be chipped on purpose in an attempt to avoid loading.
Other common causes of edge damage include:
- Improperly clamped workpiece: This can cause excessive vibration or chatter that can lead to edge damage. Be sure the workpiece is properly clamped.
- Cutting too far away from the clamping area: The farther your cutting area on the workpiece extends from the clamp, the more it moves while cutting — resulting in excess vibration or chatter. Cutting as close as possible to the clamp minimizes vibration and allows you to cut more efficiently and faster. The cut line should be as close to the clamp or mounting point as possible while still allowing appropriate clearance for the tool, guard, and operator’s hands.
- Grinding with cutting wheel: A cutting wheel should never be used for grinding; the two products are designed and reinforced for different uses and techniques. A cutting wheel should always be used at a 90-degree angle to the workpiece.
Solve common problems when cutting metal
Understanding these problems associated with cutting wheels can help you best define the cause and implement the right solution. Operations can save time and money — and reduce safety risks — when cutting wheels are used properly.
Before operating the tool, always read the instructions for safe work that are enclosed in the packaging and printed on the product label.