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Keys to Success When Launching a Transfer Job

By: Paul Stirrett

Paul Stirrett is vice president of sales, Linear Transfer Automation, Barrie, Ontario, Canada; 705/735-0000, www.lineartransfer.com.

Wednesday, July 01, 2009
 
 
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After many years of being involved in numerous transfer projects, we thought it was time to develop a list of all of the key factors we believe are instrumental in launching a successful transfer project, as well as a list of all of the major pitfalls to avoid during project management. With the recent evolution of servo-transfer systems, stampers and die makers have a host of new opportunities to improve productivity and quality. Transfer-system suppliers using customized servo-sizing software and developing machines with robust and reliable mechanical systems and with few (if any) wear components should result in a press line that runs at rated speed or above, shift after shift.
The front-and rear-mounted transfer system
The front- and rear-mounted transfer system shown here is mounted on a
1500-ton mechanical press, with 256 by 96-in. bed, at Metrican Stamping,
Dickson, TN.

The Right Equipment Combination

A new transfer-automation project begins with careful and proper selection of the right press and style of transfer system. Errors made at this stage can prove very costly. Issues to focus on include understanding the impact of link motion to the transfer automation timing and motion profiles, maximizing the range of motion on the transfer automation, accounting for interferences with other equipment around the press, quick-die-change procedures, and selecting the right style of transfer for the application(s).

Here are some of the differences between the two styles of transfer systems.

Window-mount—Advantages

• Occupies minimal space around the press, as the equipment mostly is positioned inside the press columns;

• An efficient design allows the system to move less of its own mass than does a front- and rear-mount transfer;

• It has bars running only through the die area, which remains wide open and optimizes accessibility when it comes time to perform die maintenance and adjust the transfer fingers.

A common method for mounting end-of-arm tooling
A common method for mounting end-of-arm tooling is use of a common plate located on the bars—which includes several fixed finger stations—shown here mounted on the inside face of the transfer rail of a front- and rear-mounted
transfer system.
Window-mount—Disadvantages

• The small press window restricts part width;

• Less flexibility with respect to the independent motion of the front-to-back rails;

• Often, the press window must be enlarged, which can add cost to a new press;

• Often not well suited to the retrofit market;

• Can be difficult to adapt for take-over transfer work, possibly requiring significant modifications to the tooling and transfer fingers.

Front- and Rear-mount—Advantages

• Mounts on any style of press, including presses lacking windows;

• Fully independent head control—front rail can run a completely different motion profile to the rear rails;

• Typically has a larger range of motion than a window-mount system, with infinite passline adjustment and no restrictions due to window size;

• Can be easily adapted to accept emergency or takeover work, using bars and fingers from other transfer systems;

• Deflection rates tend to be less than with a window system, because the transfer rails are held at points in the center;

• Robust design capabilities allow heavy payloads to run at maximum rates.

Front- and Rear-mount—Disadvantages

• Takes up more room on the front and rear of a press, which can be a disadvantage with rolling bolsters and during die changes performed with an overhead crane. Longer tracks are needed to ensure that the bolsters extend past the transfer’s footprint.

Teamwork, from Start to Finish

A servo-transfer system mounted on this 250-ton gap-frame press
A servo-transfer system mounted on this 250-ton gap-frame press automates stamping of deep-drawn components.

All successful projects start with a room full of the key players selected for the project being on the same page. The metalformer should ask the question, “What can go wrong,” of the press supplier, transfer source, die shop and the feed-equipment vendor, as well as his own key personnel. This process sets a tone from the start that finger pointing, once the project gets underway, will not be tolerated. This is the time to identify early-on any potential problems that might occur, and to account for them. From this meeting should come a set of master task lists and schedules, to be shared with the team and updated throughout the project.

No vendor can work in isolation from the others. High among the concerns of the companies developing the transfer system and tooling are the motion profiles, tooling interference curves, and motion strokes for optimum tool design and transfer performance. Working together, the vendors must avoid any interference from pins, cam drivers, heel blocks, etc. with the finger tooling during the stamping process.

Other key issues to address include transfer-finger designs and clearances for the end-of-arm tooling in the dies. Perform a transfer-interference analysis and run-at-rate analysis to identify, address and rectify any potential issues during the tool-design phase. Waiting until later in the project to perform these studies can prove very costly. The use of internet-based meetings and online design-review tools allows these meetings to occur cost effectively and successfully. This is particularly true for programs where dies are being built offshore.

 

 
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See also: Linear Transfer Automation Inc.

Related Enterprise Zones: Automation, Presses


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