Thomas Industrial Library

Quick Results

Figure 2-3-6 shows the most important calculated parameters. The first item shown in the calculations is the surface finish. If no static stiffness constraints or available machine power constraint occurs, then the surface finish in the finishing operation should be the same as the requested surface finish. The next item is the Specific Metal Removal Rate Q’. For certain fluids, the Q’ cannot exceed a certain value. In case this occurs, it will appear in the messaging box. The other calculated values are important but need no detailed discussion.

Fig. 2-3-6 Quick Result page of the Throughfeed One machine with multiple passes showing the calculated parameters and production rate. (Bethel Technologies, Inc.)

The messaging box shows the factors that can occur that could limit the production rate. Whenever there is enough system static stiffness available, the software calculates at what CPK value the job should be able to run. The message box suggests changes to increase productivity whenever possible.

Machine Setup

The Machine Setup page is shown in Fig. 2-3-7. There are four items that are shown in this page.

Fig. 2-3-7 Machine Setup page of the Throughfeed One machine with multiple passes. (Bethel Technologies, Inc.)

If a machine picture is available, it would be shown in the upper left corner.

The upper right corner lists the machine manufacturer, the machine model, the static stiffness of the machine when built, and the date of the last static stiffness test.

The lower left corner shows a graph of the static stiffness of the machine as a function of time. In this example, the static stiffness of the machine is slowly deteriorating.

The lower right hand corner shows the machine setup. ■ The center height is the height above the centerline of the grinding wheel spindle and regulating wheel. The calculated center height is close to the actual center height that should be used in the actual machine setup.

· The throughfeed angle is the angle at which the parts are fed through the machine.

· The diamond setover is calculated for proper contact line across the regulating wheel.

Work Blade Setup

Most work is centerless ground with its center above the centerline of the grinding wheel, Fig. 2-3-8. However, factors such as the part diameter, its physical characteristics, type, and diameter of the grinding wheel influence this setting. Generally for parts up to 1.00 in. diameter, adjust the blade until the

Fig. 2-3-8 Machine Setup Contact Geometry. (Bethel Technologies, Inc.)

part center is above the wheel center about one-half the part diameter. For larger diameter parts, the part center should rarely exceed .50 in.

If the part being ground is too high above the centerline of the wheels, chatter generally occurs. This is caused by the tendency of the wheels to raise the part out of contact with the workrest blade. If the height of the part above the center is reduced too much, the part is ground with three high spots.

The graph in Fig. 2-3-9 shows the Machine Power while the graph in Fig. 2-3-10 shows the Static Stiffness of the sample part ground in this example.

Fig. 2-3-9 Machine Power Display. (Bethel Technologies, Inc.)

Fig. 2-3-10 Static Stiffness Display. (Bethel Technologies, Inc.)