Without being able to automatically gag punches in or out on any stroke of the press, the prenotching setup for some lines would have to be changed--with much more expense involved (possibly additional presses), much lower line speeds, and in many cases could not be done at all except in secondary operations.
In a roll forming line, the dies are tightly confined. And to pull a die out in order to change punching configurations can be very time consuming, especially when large dies are involved. To minimize this change-over time, which can sometimes take hours, manual gags and/or ball-lock punches should be used whenever possible.
If changeover time is converted into potential production, the direct loss can be substantial in some cases, and also can mean tying up a line which could be running other items.
One of the main objectives in turning to roll forming, besides increased production volume, is the lowering of direct labor costs in the product. The key to just how much can be eliminated is in the auxiliary tooling such as the prenotch and cutoff dies.
A line that has a prenotch and a cutoff press, if there is an automatic dump table, might need three men to run it. Two of these men handle parts, and a third man watches the entire line and takes care of changing or the direction of changing the coils. If that same part was still roll formed and cut-to-length on the line but needed secondary punching, we would probably need at least two additional men and one additional press--usually more.
Direct labor costs are bad enough, but other labor problems gain in magnitude the more labor we involve with each product. (1) More supervisory personnel are needed, (2) more facilities must be provided, (3) total fringe benefit costs are up, (4) absenteeism becomes a problem, etc.
Space savings in this day of high cost-per-square-foot of plant space can be substantial. When secondary presses are eliminated, we eliminate the need for handling space between stations, the need for press space, and the need for storage space for the parts between operations, all of which can be substantial. In terms of 10 to 30-foot long parts, the additional space required for secondary operations becomes astronomical when compared with the space required for the roll forming line on which everything is done.
If no available floor space is the reason (and many times it is) that you are not producing other products or not increasing the production capacities of present products, then the benefits to reap from doing everything on the roll forming line in order to eliminate the space required for secondary operations are tremendous.
Another side benefit of eliminating secondary operations is the decreased risk of damage to prepainted or plated parts by handling. Any time a part must be shifted from one station to another, there is a risk of damage.
When all operations are done in line, there are less scheduling problems involved. However, when secondary operations are involved, scheduling of men and machines is another headache that must be figured out.
