Re-sharpening should never require the removal of more than 0.005 to 0.010 inch of carbide. The typical procedure for re-sharpening depends on the type of grinding operation that is required. If the procedure is to re-sharpen a dull tool, then a diamond wheel of 100 to 120 grain size is normally recommended. However, a finer wheel of 150-grain size is sometimes utilized in order to obtain a smoother finish. Some machine shops prefer to rough grind carbide with a vitrified silicon carbide wheel, the finish grinding is usually accomplished with a diamond wheel, with a final process designated as lapping may or may not be used to obtain an extra-fine finish.

Milling cutters can be sharpened by using the periphery of a disk wheel or the face of a cup wheel. The face of a cup wheel grinds the lands of the teeth flat, while the periphery of a disk wheel will leave the teeth slightly concave back of the cutting edges. The concavity created by the dick wheel will reduce the effective clearance angle on the teeth. This effect is more pronounced with smaller diameter wheels than with larger diameter wheels. It is for this reason that large diameter wheels are preferred for sharpening milling cutters.

Manufacturing technology associates are highly trained individuals who offer engineering solutions to problems encountered in manufacturing design and production. Manufacturing technology associates have an understanding and knowledge of engineering principles. These are only a couple of the many job opportunities in metalforming. Many metalforming companies today provide their employees with fair and competitive compensation packages. Many of these packages include health care, pension plans, profit sharing, paid vacations, etc. If you have great math skills, like to work with your hands, and are good at problem solving, then consider metalforming as a possible career.

Today, they are powered by electricity and can be operated manually, or under automatic control. The early machines had flywheels that stabilize their motion as well as an intricate system of levers, and gears that controlled the machine as well as the piece that were being produced.

Numerical control or NC machines were developed after World War II. These machines used a series of numbers punched onto paper tape or cards to control their motion. Then by the 1960s, computers were gradually added to the machines to allow for more flexibility in the process. These new computerized machines were then know as computer numerical control machines, or CNC for short. With the development of the NC and CNC machines, more pieces that are complex could be produced. The reason for this is that these machines could precisely repeat sequences over and over.

It wasn’t long before these machines drastically changed the cutting and shaping of tools being used. An example of this change is the drill machine, which because of computerization can contain a magazine loaded with a variety is sizes of drill bits used to produce various size holes. In the past, the machinist would have to either manually change out the bit or completely relocate the piece being worked on to another station in order to perform the different operations. Both methods took time, thus reduced productivity.

Once the NC and CNC proved to increase production, the next step was to combine various machine tools together with each being controlled by a single computer. These combined machine tools were then known as machine centers, and like their predecessors, have dramatically changed the way parts are created. Today, highly complex machine parts can be finished in a matter of minutes instead of the hours that it used to take.

Dry grinding is the method most commonly used because when an operator uses wet grinding, they tend to us an insufficient amount of coolant in order to have a better visual of the grinding operation. Unfortunately, this increases the likely hood of checking or cracking.

However, wet grinding does have several advantages over dry grinding. When sufficient amounts of coolant are used on the wheel: The wheel can be used approximately one grade harder than in dry grinding, which increases the life of the wheel. The use of sufficient amounts of coolant prevents thermal stresses and cracks. There is also less of a tendency for the wheel to load. A dust exhaust system is not required with wet grinding.

When used correctly, both wet grinding and dry grinding provide satisfactory results.

Those that cut with their ends and on their sides are called end mills, whereas milling cutters that cut with their ends only are referred to as face mills. The creation of a flat face on the work piece, thus the term face mills. Face mills generally have larger diameters than the width of the workpiece, which is being faced. This means that the surface of the workpiece can be processed in a single pass. The largest types of face or end mills are shell mills. These mount onto an arbor, instead of having an integral shank.

Slab mills cut with their peripheral edges and generally have helical cutting edges. Slab mills are normally mounted horizontally to create plane finishes on the workpiece. Plunge mills are designed for plunging the cutter directly into the material being milled, whereas single angle cutters have one side angled in order to produce a chamfer or angle on the edge of the workpiece. Single angle cutters are angled on one side to produce an angle or chamfer on the workpiece edge.

The dovetail is specially designed tools used for cutting a dovetail groove into a workpiece. A dovetail is a fan-shaped tenon, which forms a tight interlocking joint when fitted into a matching mortise.

Keyseat cutters are used to produce a slot that acts as a seat for a corresponding engagement key. Keyseat cutters are used to key shafts to prevent unwanted rotation and provide positive engagement. The side cutting edges of the T-slot cutters feed into the workpiece to produce a “T” slot.

To create a convex feature or a male semicircle on a workpiece concave formed cutters are used, on the other hand, in order to create a concave feature or a female semicircle, convex formed cutters will be used.

To cut tooth forms on gears, machinists use gear hob milling cutters and to produce teeth of an involted form gear hobs and cutters are ground.

Button or copy cutters use round inserts known as “buttons” instead of square or triangular inserts. The round inserts permit enhanced feed rates and depth of cuts using lower power.

Titanium nitride (TiN) TiN-coated carbide end mills must be run at speeds and feed rates close to that of uncoated carbide end mills. However, the TiN coating provides a better wear and lubricity to the end mill.

Titanium carbon nitride (TiCN) TiCN coatings are perfect for slow feeds and speeds, however it is often the choice coating for high-speed steel end mills. For carbide tools coated with TiCN, you can run at speeds approximately 80 % faster than uncoated solid carbide end mills. However, TiCN is prone to failure under extreme heat, which is why it is often used in slower feed and speed applications.

Titanium aluminum nitride (TiAlN) or Aluminum titanium nitride (AlTiN) TiAlN- or AlTiN-coated end mills are becoming increasingly popular. The aluminum in both coatings helps to create a gaseous aluminum oxide layer at the cutting edge that can reach temperatures greater than 1800-degrees. This layer of aluminum oxide gas protects the carbide in the tool from the damaging effects of heat. This is why these two coatings have become popular for high-speed and hard milling, especially in dry cutting. Aluminum titanium nitride contains greater amounts of aluminum than titanium aluminum nitride.

There are other coatings available on the market today, however, they are variations of the main three. When machining nonferrous materials, aluminum, brass, and plastics non-coated carbide end mills that have polished flutes are recommended in order to prevent edge buildup. These materials require finely keen edges and end mills that are coated don’t allow as sharp an edge.

These are only a few of the factors to consider using carbide end mills. Other factors include the specific geometries of the end mill, rake angles, gash lands, relief angles, as well as programs, and the machine. Understanding the process as well as the material that will be machined is only the first step in deciding which end mill should be selected for the application.

There is a wide category of end and face milling tools available, including flat bottom, ball nose, radius, inverted radius, and chamfer tools. In addition, each of these categories can be further divided by specific application and special geometry.

More and more traditional solid end mills are being replaced with better cost-effective inserted cutting tools. These end mill tools are initially more expensive. However, inserted cutting tools do reduce tool-change times and permit for a much simpler replacement of worn or broken cutting edges instead of having to replace the entire tool.

Both metric and imperial shank and cutting diameters are sold in the United States and in Canada. However, in the United States, metric end mills are not commonly used in every machine shop where as in Europe and Asia they are the standard.

End mills are used several different types of milling applications including profile milling, tracer milling, face milling, etc. The tool that is used will depend on the material, which is being milled, as well as the particular task that has to be performed.

End mills have flutes, which are spiral cutting edge on the end mill. End mills can have between 2 to 8 flutes, with most end mills having 2 and 4 flutes. End mills that have 2 flutes allow for the maximum amount of space for chip ejection and are used for general milling procedures. End mills with 3 flutes are perfect for slotting as well as general milling. End mills with 4 to 8 flutes reduce chip load and provide for a better surface finish.

Just by the nature of the process of high-speed machining with micro tooling heat. In fact, the process creates enough heat that can require the use of coolants, even though HSM technology contains advantages, which reduce heat. There are, however certain applications that still require the use of an efficient coolant system.

Coolants perform two task, first the reduce heat and second they serve as a lubricant, which enabling the tool to move smoothly over the surface of the workpiece. Micro tooling requires a lubricating agent that has a viscosity lower than water in order for the coolant to make it to the cutting edge of the tool at the higher spindle speeds. Emulsion-based coolants are ineffective as a lubricant for HSM with micro tooling because they have a higher viscosity than water.

Ethanol can be used in micro-volume coolant spray systems and is suitable for nonferrous metals as well as some plastics. However, oil-based coolants are required on steel-based materials because of the risk of sparks that can be produced by the carbide tooling on steel surfaces can produce a safety hazard when the sparks come in contact with the ethanol.

Although ethanol is flammable, its low evaporation point makes it an efficient coolant for HSM operations. Other benefits of ethanol include that fact that it doesn?t leave any residue on the machined parts, and eliminates the process of degreasing.

Improving HSM Technology:

Machining involves math, a lot of math. We use math to calculate the areas and dimensions of plane figures, we use math for measurements and inspections, to check pitch, to calculate clearance angles, and speed and feed rates, in fact there probably isn?t a step of machining that does not relay on a mathematical formula. Therefore, it is perfectly logical and mathematically sound when we state that a smaller tooling requires a higher spindle speed in order to machine the parts efficiently. This is due to the fact that the higher spindle speed is required to efficiently evacuate chips to prevent chip burn-up.

HSM technology does use higher rpm rates, however it also uses considerably increased feedrates as well. When the spindles spin fast, there’s not enough time for heat to feed back into the workpiece and cause concerns. However, the tool continuously cuts chips from the workpiece, which produces heat and friction on both sides of the tool and chip. Approximately 60% of the heat is inside the chip. HSM process is based on evacuating the chips, thus removing the heat along with the chip to provide a cleaner cut. However, if the tooling cannot or has insufficient chip evacuations, then the heat is not removed, creating chip-burn and eventually the tooling cracks, and breaks. A better principle would be machining process that is based on cooler tooling, meaning lower machining forces to reduce vibration. Higher spindle speeds reduce the amount of chip load to < 0.005″, which in turns reduces the amount of forces between the tool and the workpiece. A higher speed lower force machine produces less heat, which decreases tool deflection resulting in a better surface quality, as well as better accuracy.

Dynamics of Machining:

Improved Micro tooling designs, low-viscosity coolant, and improved HSM technology can drastically improve the dynamics of machines, which perform HSM with micro tooling. Traditional machines are heavier meaning that they do not have the speed or feed rates required for micro tooling. Therefore, you cannot expect the same quality, precision, and tolerances from retrofitting a high-speed spindle onto a traditional machine as you would from a high-speed machine with micro tooling that is designed precisely.

Machines can either be large and powerful capable of using tools with large diameter spindle sized, or they can be lightweight, designed specifically for micro tooling. When you attempt to merge the two, it is like trying to breed a Great Dane and a Tea Cup Chihuahua. Therefore, to achieve proficient high-speed machining there has to be improved micro tooling designs, the use of low-viscosity coolants, and improved HSM technology. HSM with micro tooling provides less force, reduced heat, which means less tool breakage, and a better surface finish. In addition, there is the elimination of deburring and the degreasing process.