Multitask machining needs industrial-strength CAM.

Author:Gibbs, Bill
Position:Software solutions
 
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You don't have to go far at a machine tool show before you hear someone complaining about the current global marketplace. There is no telling where your next machining competitor is going to be located, with China being mentioned the most often. A big advantage of these far-off locations is their low cost of labor. The best way to compete is by reducing the labor cost of the parts we manufacture. This is exactly what multitask machining, or MTM, machine tools do.

As the name suggests, MTM machines do more than a single machining task in a single setup. A single-task machine is a basic mill or lathe. In the old days, most parts required multiple setups on multiple machines. When you take a close look at the labor costs in this style of manufacturing, it's surprising how much labor is involved with each setup, with each part transfer, and with the inspections required at each step. Just moving and storing incomplete parts around the floor is expensive. Machine time is not the only expense. To be accurate, you have to factor in a significant cost of scrapped parts. Each setup introduces an in creased risk of human error and of scrapped parts. Of course, this invariably occurs and is detected in the last operation.

MTM machines range from simple to complex. The simplest MTM is a lathe with a sub-spindle--able to perform work on two sides of a part, the equivalent of two setups. But this part transfer is automatic, and the alignment between setups is as good as it gets. You can add live tooling, B and C rotary axes, a Y-axis, and a second turret to support two tools cutting at the same time. This style of MTM is called a twin turn. Instead of turrets, some MTM machines use a mill-style automatic tool changer (ATC) with a B-axis on the tool spindle. As these machines grow in size and horsepower they look more like large five-axis mills, not lathes, but they still combine and perform well on both types of machining. The Mazak Integrex machines are a good example of this kind of CNC. MTMs don't stop with two tools cutting on two spindles. Models can be found with three, four, or more tools cutting simultaneously, as they transfer parts through any number of part spindles. Some popular configurations use Swiss-style sliding headstocks, and sliding gang-tool changers. Others include programmable steady rests, programmable tailstocks, bar feeders, bar loaders, part catchers, part grippers, robots, etc. The range of MTM machine model configurations is...

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