Introduction:
Milling machines rotate at high speeds and therefore carries the risk of shavings and chips of metal flying all over the machine while it is operating. It is important to think safety at all times while operating the milling machine. Do not operate the machine if you are not familiar with the safety rules and precautions. The following is a guideline to operating the milling machine safely.
Wear the correct PPE (Personal Protective Equipment)
PPE include the following
- Safety glasse to protect your eyes against flying shavings metal chips
- Overalls or coats without long wide cuffs to protect clothes. (wide lose cuffs can get caught in rotating machinery)
- Appropriate safety boots/footwear to protect feet against injury.
- A safety cap or hair net to cover long hair that can get caught in revolving machine parts.
Make sure all machine gaurds are in place
When operating a milling machine the operator must ensure that machine gaurds are in working order and in place on the machine. All workers in the workshop is safer with the machine gaurds in place.
Machine gaurds are normally put over all revolving machine parts, such as gear assemblies, motors and couplings. Some machines will not start if the machine gaurds are not in place.
Provide enough space around a clean work area
- Do not clutter the workspace with unnesessary equipment, tools and materials.
- Keep the work area clean and dry. Clean up coolant and oil spillage immediately
- Allow enough space around the work area for loading and unloading of work.
- Demarcate areas for finished goods and raw materials
- Remove all chips, offcuts and shavings from the machining area.
- Tools and equipment must be stored in a storage area.
- Keep the floor area clean, dry and oil free to prevent slippage and accidents.
General safety rules:
- Use Gloves when mounting Milling cutters. Milling cutters have sharp edges and wearing gloves prevents small cuts on fingers.
- Switch off the machine before loading or unloading workpieces to prevent injury by rotating cutters.
- Switch off the machine when you do measuring or cleaning.
Plan your work on the Milling Machine.
The following factors should be kept in mind when planning your work on a milling machine.
- Spindle speed: This is the rotational speed of the cutting tool and it is measured in revolutions per second.
- Tool diameter: The size of the cutting tool measured in diameter.
- Feed rate: The rate at which the material is fed into the milling machine. This is measured in mm/min.
- Cut depth: The amount of material that is cut away in one pass. This is measured in mm.
- Surface cutting speed: the speed that each tool cut through the material. This is measured in m/mm
Diffirent cutters used on the Milling Machine.
On the Milling Machine you will use diffirent cutters to achieve diffirent cuts and finishes on a work piece. We will look at diffirent cutters but please note that you will find many more specialised cutters in the engineering environment.
- End Mill Cutters: This is the most commonly used cutter to use on a milling machine. The cutter rotates on a vertical axis in relation to the workpiece but it can be tilted to produce tapered surfaces.
- Face Cutters: These cutters rotate perpendiculer to the workpiece. It is mostly used for facing with cutting edge on the face and edge of the cutters.
- Ballnose Cutters: These cutters have a round (ball or hemispherical) shape. They are used to form round grooves or three-dimentional shapes.
- Slab cutter: The cutting teeth are on the uotside edge of the cutter and the cutter rotates parallel to the workpiece.
- Side and face cutter: This cutter has teeth on it side and Circumference which make it possible to cut on one side only.
Determining the cutting speed
The most common mistake made with cutting speed is a result of presure to produce. Using the correct cutting speed is important or else the milling machine, cutter or workpiece can be damaged with a loss in production time as result. Here is a typical recomended cutting speed chart.
Calculations for milling operations are being look at seperately so please browes the blog for more milling machine information.
