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Tag Archives: milling tutorial

OPERATING THE CNC MACHINE TOOL

Manual Data Input Manual data input, or MDI, as its name implies, is the mode in which program data may initially be entered using the CNC’s keyboard. MDI mode also allows for editing or deletingn existing program data. A complete block or complete program may be entered and run in MDI mode. However, once the data are …

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INCREMENTAL POSITIONING DIMENSIONS—G91 MODE

In incremental mode, each programmed motion is independently measured from the previous point (Figure M-35). For example, the drawing shows a four-hole pattern with each feature dimensioned relative to the other features. If the part were to be drilled starting from the setup point indicated, each tool positioning move would be an increment equal to the drawing dimensions. Positioning from the …

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WORK HOLDING AND CENTER-HOLE GRINDING

The workpiece in on-centers cylindrical grinding is mounted between the head and footstock centers. This effectively provides a single point mounting on each end of the workpiece, permitting maximum accuracy to be achieved in the grinding operation. The angle and finish of center holes in the workpiece is extremely important. The results of a cylindrical grinding job depend on …

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SURFACE GRINDING BASICS

Horizontal spindle surface grinding is becoming ever more important as equipment and machined parts are miniaturized and dimensional tolerances shrink. A few years ago, ;.0001 in. was considered a close tolerance. Now, half that amount (.000050 in.) is seen more frequently on drawings, especially in the advanced technology areas. These pressures for increasingly closer work are …

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TYPES OF GRINDER CHUCKS

Magnetic Chucks The most common work-holding device for the surface grinder is the magnetic chuck. The three types are the permanent-magnet (Figure L-79), the electromagnet (Figure L-80), and the electro-permanent-magnet chuck.Permanent-magnet chucks, which are the most widely used chucks in the job shop setting, are composed of a series of alternating plates consisting of powerful …

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ACCESSORIES

The versatility of the horizontal surface grinder can be extended by the use of accessory equipment. Several of these pertain to work holding and will be discussed in the next unit. Accessories that increase the grinding capability of the machine include the following. Centerless grinding can be accomplished using the centerless attachment (Figure L-77). Parts …

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CLEANING THE GRINDING FLUID

However, many grinding machines have self-contained grinding fluid systems. Several methods are used for grinding fluid cleaning. Cleaning of the fluid should be carefully done and monitored. A fundamental technique is settling. Grinding fluid is pumped to the settling tank, where swarf settles out by gravity. Settling tanks should have a series of baffles and enough …

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TRUING AND DRESSING

When a new wheel is installed on the grinder, it must be trued before use. The cutting surface of a new wheel will run out slightly due to the clearance between the wheel bore and machine spindle (Figure L-51). Truing a wheel will bring every point on its cutting surface concentric with the machine spindle. …

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CONCENTRATION

Concentration is a term applied to superabrasive grinding wheels that refers to the amount of abrasive contained in a unit volume of usable grinding wheel. A concentration of 100 corresponds to 72 carats in a cubic inch of wheel in the effective superabrasive volume of the grinding wheel. The concentration values are usually between 30 and 175. …

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TYPES OF GRINDING MACHINES

The versatility and wide application of the grinding processes have led to the development of many types of grinding machines. Your shop will probably have two, three, or more of the common types. As a machinist, you should be familiar with the many types of these machine tools and the processes they perform. Surface Grinders One of the most common grinding …

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