404 Why Choose A Tube Fabricating Work Cell?
Problem ---
-When Joe feels the "Call of Nature", his operation stops
-When Joe takes his morning break, his operation stops
-While Joe listens to Sam's bowling scores, Joe's and Sam's operations stop
Joe gets pretty good pay and benefits even while his operation stops
1. Raw Material
2. Manual Load
3. CNC Bender
4. Manual Unload
5. Goods in Process
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Starting a solution ---
Step one:
Get rid of the start button at the beginning of each cycle, have a man unload the machine only, then the machine's pace regulates the man rather than the man's pace regulating the machine.
1. Raw Material in Automatic Loader
2. CNC Bender
3. Manual Unload
4. Goods in Process |
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Step two:
Automate the unloading function with a robot; now machines regulate themselves and never stop for nature, breaks, or bowling.
1. Raw Material in Automatic Loader
2. CNC Bender
3. Robot Unload
4. Goods in Process |
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Step three:
Add Sam's job up or down line, then add other jobs.
1. Raw Material in Automatic Loader
2. CNC Double End Forming Machine
3. Robot Unloads and Transfers to:
4. Automatic Single Part Loader
5. CNC Bender
6. Finished Goods |
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Time savings ---
Many companies get 55 minutes of work per hour per man which means they lose 40 minutes of production every 8 hour shift. They also lose time to scheduled breaks, 15 min. morning, 30 min. lunch, and 15 min. afternoon break. This brings lost time to 1-2/3 hours per man each shift, and then there's vacation time. In one year an automated work cell system works an additional 486 hours for each man it replaces, excluding maintenance for both the man's machine and the system.
The benefits of time savings are in addition to; increased parts per hour and quality, increased consistency of production, increased predictability, reduction in set up time, and reduction in scrap.
Basically, the companies that reduce their costs through work cells achieve a much better position to compete price-wise with foreign labor and products while remaining profitable. |
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Here are some areas where cost savings can be generated with the use of work cells as compared to a conventional shop floor:
Less Set Up Time ---
The first time a part is run, any CNC machine needs to be programmed (or an old program modified) and the new program saved. Set up for the next run is "tweaking" only. The time this saves for long runs is appreciable and the set up time savings for a series of short runs is tremendous.
When a number of these machines are grouped together, coordinating the part number to be run with the proper programs for each of the many machines in a work cell can be time consuming. However, the operating programs for each CNC machine in a system can be stored and distributed by the master controller. That's when a communications link to each CNC machine in the system can save time and money by providing central program storage and distribution.
The flexibility a master controller brings to a system reduces scrap also, both in set up and during the run. As the level of machine control improves it becomes easier for the operator to identify and correct problems at their source.
A master controller gives the operator lots of options in correcting a problem. Machine programs can be modified either at the master controller console or at the machine. Changes can be made with the system running or stopped. The result is less setup scrap and less production scrap.
A System Communicates ---
The master controller provides a communications net between machines. It stores and delivers the operating programs to the individual machines for use on a given part. While the system runs, the master controller coordinates and monitors the operation of each machine, ready to shut the system down if a problem occurs.
Bringing all the different machines found in a typical tube fabricating system together under one master controller is a real problem. Different machines require different levels of control; like a drill press compared to a bender.
One solution is to use only one kind of general controller and build it up or down to suit the level of sophistication required by each machine in the system. At all levels the same communications format would be used so everything can plug directly in to the master controller. The controls for each machine (proximity sensors, encoders, etc.) must also be compatible with that machines' controller.
Less Inventory ---
A major reason for creating work cells is that the amount of goods in process can be reduced, which means that you have less inventory to pay for. If all the machines required to produce finished goods can be arranged in a group there will be no goods in process sitting around in bins.
Quality Control ---
Use of in process gaging which locates the part for the next operation based on a feature of the last operation. This won't allow a bad part to be processed through the next operation.
Trouble Shooting ---
In process gaging prevents the first bad part from an operation from being processed through the next operation. So, you go directly to the cause of bad parts instead of sorting through many operations.
Scrap Control ---
You have better control of scrap, eliminating the chance to run baskets full of automatic junk and not discover them until they reach the next department.
Labor ---
In a work cell a person picks a part from a bin and puts it into another bin (if not into an assembly) only after all subsequent operations have been completed. Every additional operation that is added means one less bin and handling. Many systems require only one operator to monitor the work and occasional material handling needed for raw or finished goods.
Hidden Costs ---
When parts are no longer transferred from department to department you may find that you have extra fork lift trucks and drivers. What about the baskets, bins, and tubs - you don't need them any more, or the racks they sat in, or the floor space they took up. During the work day there will be less production time wasted waiting for fork lift trucks to bring parts.
Through-put And Profits ---
The bottom line is that more sellable parts will be produced in the same amount of time and with less cost of production. That means bigger profits to take to the bank.
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