Automating a turret-punch press can be a quick way to dramatically increase productivity along with streamlining a shop’s material handling. But is the productivity enough to outweigh the costs?
There are many reasons to automate a punch press mentions Dan McIntyre, punch press product sales manager for LVD Strippit Inc. “Automation frees up your operator to do other things. It’s also much more efficient at moving material to and from the punch press while helping the company keep track of their inventory for blanks and punched parts.
“If an operator is loading 4 ft. by 8 ft. sheets on a punch over an eight-hour shift, productivity might drop as the shift goes on, as the operator has to unload these large heavy blanks throughout the day. An automated-punch-load/unload system allows the punch to run continuously throughout the day.”
Cary Teeples, central regional manager for Murata Machinery USA, Inc., says that his company built the first FMS in 1977 in Japan and the company’s customers have been experiencing the higher productivity of these systems that the automation offers.
“The benefits are multiple,” he notes. “Obviously there is a cost reduction to punching sheet metal, because once you have the predictability of throughput in a system, it provides manufacturing engineering more consistent information on production, helping to better manage costs.
“For instance, I have a customer that has door manufacturing facilities in the U.S. and Mexico. They have an automated punch-press cell and get about 514 doors out of the one cell per shift on one machine. What they get from two manually run machines at another plant in one shift is only 419 doors. So there is a significant increase in productivity simply by automating the punching process.”
Both Murata and LVD Strippit make automation systems that are designed for only their equipment. LVD Stippit’s automation can be scaled from a small unit that only has one pallet and equipment to move the sheet metal into the punch, to a much larger tower-style system to manage far more material.
Murata does not offer a scalable system. But Teeples mentions that if a company has its automation, and wants to expand, they can usually sell the automation system and replace it with a larger one.
When the machine manufacturer doesn’t offer automation
Most turret-punch press manufacturers offer automation for their equipment. But sometimes a company might not offer automation or the punch can’t be retrofitted if its older. In this case, automation is available through a secondary supplier like Kasto.
Kasto offers automation for any type of CNC equipment. Werner Rankenhohn, Kasto’s president, says, “Many companies that build fabricating equipment have their own automation and storage solutions. However, we do things a little bit differently. First, we don’t make sheet metal processing equipment. We come from the automation side by making storage-and-retrieval systems. About seven years ago we decided to get into the sheet-metal business to provide a storage solution for companies that didn’t provide it for their equipment. If you have four different machines in one shop, they can all be linked together with our Kasto storage-and-retrieval system.”
A Kasto system has a number of pallets stacked on top of each other in a tower. There is a lifting mechanism that travels up and down that picks a pallet that holds the raw material and moves it down to the sheet separator that takes the individual sheet from the pallet and puts it on the in-feed table of the sheet metal processing machine.
Rankenhohn mentions that the fewest amount of pallets that would make financial sense would be somewhere in the 10 to 15 range. “A pallet itself is a steel pallet welded together from steel tubes. The money lies in the lifting equipment that rises up and down and brings the pallet to the unloader station and the controls that do all this. Once you pay for these two basic elements, adding pallets to it is a relatively insignificant increase in cost. A pallet system that only has two or three pallets really doesn’t pay for itself.”
Kasto’s equipment is primarily designed to move raw materials to a CNC machine and not take finished parts away from it. But they can remove parts that are still connected to a large sheet and offload them to a manual secondary operation to separate the parts from the sheet-metal skeleton. Then these parts can be placed on another pallet and stored in the tower.
Single pallet load/unload
LVD Strippit offers a single-pallet load/unload system that can be expanded into a multi-pallet tower system. The system can move raw material from storage to the punch and also take finished parts from the punch to storage.
The tower allows storage and loading of different types of materials, thicknesses and sizes into the punch automatically.
Once finished parts are produced, the parts along with the skeleton are automatically taken off of the punch press and loaded onto another pallet, says McIntyre. “This type of system would work well for a lights-out manufacturing,” he remarks.
McIntyre did point out that the company’s single pallet can be used with different materials and sizes on the pallet to process material without an operator.
He notes, “It can do this, but it certainly requires more intervention and planning ahead. If there are no full-sized blanks, the smaller blanks will have to be placed on top with the larger blanks on the bottom. Then the software program needs to know which blank is where. For the most part, it’s really best to put the same material and size on the pallet. But if production is really well organized, the pallet system can work with different sized blanks and materials, but it’s really not designed this way.”
Justifying punch press automation
Justifying this type of automation can be done in several different ways, says Teeple. ” “Automation can be justified with productivity increases along with a decrease in labor. Industry wide the average green-light time for a stand alone punch press 30 to 35 percent. These numbers were generated by an industry study looking at a cross section of users. By adding a loader to a punch press, the shop can increase their productivity up to 60 to 65 percent. Why, because the automation is eliminating the smoking breaks by the operator, lunch and the slower processing times that could happen in the afternoon or morning. Also, a part run isn’t subject to the operator having a good or bad day.”
Another justification is related to a reduction in costs by eliminating post-process costs by using post-part sorting automation.
Generally speaking says Teeple, “most companies will run a spreadsheet to look at their costs to see if they can justify an automated tower system. They will look at labor costs along with a reduction in their piece-part costs and an increase in productivity. So these three factors drive the justification for automation in most cases. And we will help a company with revealing this information.”
McIntyre adds that it’s also about the mix of product that the end user is using along with volume they’re producing. “If a shop is doing one-offs, the loader would not provide the benefit that’s needed. But for larger runs of similar materials, for instance, 100 sheets of 16-gauge mild steel is all that’s run, the loader would work perfectly, because there’s a standardized blank size along with the material type and thickness.
“Here automation would give a company greater capacity, more throughput, less operator fatigue and possibly the elimination or reduction in hours for an operator. A company would have to factor in all these costs to justify having a load/unload system.”
When raw material is brought into a facility it has to be stored somewhere, remarks McIntyre. “When it’s stored on a pallet in a tower system, the next time that it’s touched, it’s a part. A person doesn’t need to retrieve the material, bring it to the machine, punch it, handle it again and take it off the machine. With a tower system, the material comes in the back door, it’s placed into the tower, and then it’s made into a part without any other manual intervention. It saves a lot from the material handling standpoint, which can slow down machine cycle times.”
Another way to justify automation says Teeple is looking at how many shifts the equipment is run. “Most job shops will justify their machine based on running one shift. The second or third shift is rather elusive and can’t be banked on. If you have automation, and it’s set up to run lights out when everyone is gone, this becomes pure profit, because all this production isn’t really being produced during the time that you’ve allocated paying for the equipment. Primarily your cost for the second and third shift in a lights-out environment is just your material costs and the costs to run the machine minus the operator.”
Murata Machinery USA Inc.