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1. Safety glasses: These prevent dust, debris, wood shavings, shards from fiberglass, etc from getting into the eyes. Safety glasses are one of the most basic pieces of safety equipment that must be used when working with power tools. 2. Protection for the ears: Power tools can generate a lot of noise, which may sound louder in the cloistered environment of a workshop; in order to minimize damage to the ears, it is advisable to wear earplugs. 3. Knowing the right tools for the job: It is important to know the right tools for the job in order to avoid injury to oneself and damage to the materials. To this end, it is advisable to thoroughly read the instruction manuals provided with the equipment and get familiar with the recommended safety precautions. 4. Correct method of using tools: Tools should not be carried by their cords; tools that are not in use should be disconnected; and while handling a tool connected to a power source, fingers should be kept away from the on/off switch. 5. The right clothes: Long hair should be tied and loose clothing should be avoided. Ideally, clothing that covers the entire body should be worn and heavy gloves should be used in order to avoid sharp implements and splinters from hurting the hands. Masks prevent inhalation of harmful minute particles of the material that is being worked upon. Steel-toed work boots and hard hats can also be worn. 6. Tool inspection: Power tools should not be employed in wet environments and should never be dipped in water; they should be checked periodically for exposed wiring, damaged plugs, and loose plug pins. Nicked cords can be taped but if a cut appears to be deep, a cord should be replaced. Tools that are damaged or those that sound and feel different when used should be checked and repaired. 7. Cleanliness in the work area: This should be maintained because accumulated dust particles in the air can ignite with a spark. Of course, flammable liquids should be kept covered and away from the place where power tools are being used. An uncluttered work area also makes it easy to maneuver the power tool; often distractions caused by a tangled cord can result in an accident. 8. Care with particular tools: Miter saws and table saws should be used with a quick-release clamp and a wood push-through, respectively. Extra care should be taken while using nail guns and power belt sanders. 9. Keep tools in place: Power tools should be returned to their cabinets after use to prevent them from being used by an unauthorized and incapable person. 10. Lighting: It is important to use proper lighting while working with power tools, particularly when working Why Does The Tool Bit Break Easily In Micro Milling? Ken Yap Micro milling is one of the three common micro cutting techniques used in micro machining. In micro milling, the tool bit with diameter as small as 0.1mm is held in a high speed spindle rotating at 20,000 to 150,000 rpm, and used to mill steel, brass and aluminum with depth of cut at about 30 microns and feed rates of 120mm/m to 240mm/m to provide surface quality finishes as good as 0.2 microns. While micro milling has been successfully applied in manufacturing bio-medical components, embossing dies and micro encoders, the breakage of the tool bit has been identified by many users as a teething problem. Why does the tool bit break so easily in micro milling as compared to conventional milling? There are 3 main reasons: Firstly, when metal is removed by machining, there is a substantial increase in the specific energy required as the chip thickness decreases. This means that in the case of micro machining, as the chip gets thinner with smaller depths of cut, the micro tool bit will be subject to greater resistance when compared to conventional machining. It is as if the workpiece material becomes harder during micro machining. This resistance force is strong enough to exceed the bending strength limit of the tool bit even before the tool experiences any significant wear, and leads to the breakage of the tool bit. One way to prevent this is to make the chip thickness smaller than the edge radius of the tool bit. Secondly, a sharp increase in cutting forces and stress from chip clogging during the micro milling process would cause the tool bit to break. In most micro milling operations using miniature micro tool bit with two cutting edges, each cutting edge removes the chips from the machining area only within half a rotation. However, if chip clogging occurs, the cutting forces and stresses will increase beyond the bending strength limit of the tool bit within a few tool rotations, and the tool bit will break. Some users prefer high speed steel tool bits as these are very much more flexible and tolerate clogging better than carbide tool bits. Thirdly, the tool bit tends to lose its cutting edge due to built-up edge and cannot machine efficiently. As the workpiece starts to push on the tip of the tool bit, the tool bit will deflect slightly. The increase in tool deflection and the stress generated by the milling with every rotation will eventually cause the breakage of the tool bit. This process is also called extensive stress-related breakage. In view of the above phenomena occurring in micro milling, most micro milling machines are sold with sensors to measure the forces acting on the tool bit, and advanced CAM software to predict the chip load throughout the micro machining process. In this way, precision manufacturers seeking a niche in micro milling could try to keep their machines running smoothly with minimal machine downtime. http://www.ezinearticles.com/?Why-Does-The-Tool-Bit-Break-Easily-In-Micro-Milling?&id=121433 | ||||||||||||||||||||
