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Editorial Note: Recently, Granco Clark has experienced a surge in orders for our proven Double Puller with “cut-on-the-fly” capability. So we felt it might be appropriate to revisit an article written by Roger Fielding that provides a good understanding of this technology, and how it can help maximize the productivity of an aluminum extrusion operation.
You don’t have to travel far to find businesses where extrusions are still being manufactured in a series of disconnected steps, where production is entirely dependent on people for the completion of each step, and for moving the extrusions from step to step.
In such operations, billets are selected from stock, or sawn from log. They are then moved to the press area and loaded into the furnace by someone using a fork truck or crane. The heated billet is transferred to the extrusion press by the press operator “calling” the billet. The extrusion process is started and controlled by the operator, and the extrusions are guided down the run-out table (and often transferred to the cooling table) by hand. Even in plants equipped with pullers, people are to be seen feeding extrusions into the puller at the start of each billet, and “helping” the transfer to the cooling table. In such operations, you can still find walking beams being used to move extrusions to the stretcher while they are cooling, and walking beams transferring the stretched extrusions to the saw feed conveyor. The extrusions are invariably moved into and out of the stretcher by hand. At the finish cut saw, the extrusions are lined up by one man, and the saw is worked by another. The cut extrusions are stacked by hand.
Earlier we showed that the true cost of poor recovery is buried in the labor, materials, and energy used to produce scrap—and in the cost of the additional labor, materials—and energy required to “do it right” the second time. We showed that understanding the problems that cause the scrap, allows us to continuously improve the whole extrusion production system. We demonstrated that modern extrusion systems have a direct impact on reducing the source of waste labor, time, and materials.
This article focuses on the operation of the Granco Clark Double Puller system and shows where it contributes to reducing waste in the extrusion plant. The multiple activity charts describe how the double puller operates in different modes and applications, and how the system is integrated with the extrusion process. The article highlights those features which increase productivity and recovery by reducing and eliminating waste.
Inconsistent Billet Weight, No Log Shear or Log Saw.
To ensure constant butt length, puller #2 is stopped by the press. This program is used when the billet weight is not controlled, or there are problems with the butt shear.
The program allows for continuous extrusion, and cutting on the fly places the die or weld mark in the stretcher scrap, but use of this program results in variable extruded lengths. And, it wastes press time by extruding scrap.
It is also used when there are problems with die and/or butt shear which could result in metal being pulled from the die by the butt shear.
Single Puller Mode with Moveable Hot Saw.
This program cuts the extrusions one customer length from the die face to maximize recovery when using the water quench.
Where space for “hand over” is limited, this program maximizes the extrusion speed which can be reached with a given die or alloy.
Multiple eXtrusions per Billet: MXB
Eliminates multiple pushes, operating “hand over hand.”
The program minimizes the waste time which occurs when multiple pushes are required to extrude light sections. Extrusion is continuous, until extrusion is stopped by the press, and the butt sheared.
Recovery is improved because the longest practical billet can be extruded. The extrusions are under tension throughout the extrusion of each production lot. Compared to the extrusion of successive small billets, only one butt is produced.
Multiple Billets per eXtrusion: MBX
Billet on billet extrusion: extruding long lengths of heavy sections.
P2 draws the extrusion down the run-out table as each billet is extruded. When the desired number of billets has been extruded, the press stops the puller and shears the butt.
Flat Face Die: Non- Continuous Extrusion.
Using both pullers eliminates the waste time which results when “waiting” for a single puller to return to the press. The program is also used with old tooling which does not justify replacing due to order frequency or order size.
Program 6Maximize Productivity and Recovery: MPR
The most frequently used program
After the die has been loaded, the extrusion is led out to the puller P2.
The extrusions are then held under tension by P1 or P2 until the die is removed from the press.
The puller stops the press the correct distance from the die face. Excess scrap is left in the butt so reducing melt losses. The exact length is extruded thereby saving time.
This program also has MXB (Multiple Extrusions per Billet) capability.
Cutting on the weld mark minimizes scrap. “The system takes the weld mark and puts it in the stretcher scrap.” John Menary, Vice President of Sales, Can Art.
The extrusion is taken to the correct position on the run out.
For Maintenance Only. These programs allow each puller to be used by itself.
BENCHMARKS: Understanding the Operation of the Granco Clark Double Puller System.
Preventive maintenance or extra service calls: it's your call.
Furnace efficiency moves to the front burner.
President's Message: Still the One.
Profiles: Serving the information needs of the international aluminum extrusion community
