Beyond nesting

Addressing the basic incompatibility of sheet metal manufacturing and ERP software

Finished product from Laser cutting metal machine

I was once one of those expensive (some say overpaid) enterprise resource planning (ERP) consultants. After you purchased my employer’s software, I’d come onsite for days, weeks and sometimes months to learn everything I could about your company’s manufacturing operations, then figure out how to make you happy with your new ERP system.

I did it for 16 years, and aside from the terrible homesickness, occasional bedbug and $10 beers at Chicago’s O’Hare airport, I enjoyed it thoroughly.

Except for one thing: I always dreaded going into sheet metal shops.


The tough questions

Don’t get me wrong – I love sheet metal. My first job was operating a turret punch, and if my father-in-law hadn’t convinced me to pursue a machining career, I’d probably still be there.

And while I recognize the importance of a good ERP system and salute the extensive capabilities, the problem at virtually all sheet metal shops was predictable. At some point during the requirements gathering workshops, the conversation eventually rolled around to the same basic question. “How are we going to manage the remnants?”

My reply was an awkward, “I’m not sure.”

The customer’s response was understandable. “What do you mean? The sales guy told us you have dimensional inventory capabilities. Where’s the problem?”

Ten minutes later, the limitations of dimensional inventory now thoroughly explained, the customer called for a break, upon which they would phone the ERP salesperson. Unpleasant discussions ensued, a credit for the dimensional inventory module was issued, and everyone went back to work.


Dimensional dilemmas

Sound familiar? If not, here’s a quick primer: As its name implies, dimensional inventory provides data fields for specifying the length, width, thickness, weight and other attributes of raw material. In most systems, these values are then associated with a lot number for material tracking, so that unique part numbers don’t have to be defined for every dimensional variation.

These lot numbers are respected during cycle counts and other inventory transactions, and unit-of-measure conversions make it easy to convert, for example, a full sheet to a half or quarter sheet, so many inches of tubing to so many pounds, etc. Pretty powerful, right?

There’s just one problem: When Joe shears 30 in. off the end of a 4-ft.-by-10-ft. sheet, the material requirements planning (MRP) engine only knows there are 30 sq. ft. left, so it assumes there’s plenty of stock available for the 2-ft.-by-10-ft. workpiece your customer just ordered. Oops.

Then along comes Marty, who grabs the 4-ft.-by-7.5-ft. remnant and laser cuts a half-moon shape out of one end. The warehouse clerk takes a best guess at the remnant’s usable dimensions before putting it back in stock, but it’s not until Jim goes to pull the thing back out that he realizes there’s not enough for his job. Expediting, downtime and late deliveries are the result.

Although cumbersome and error prone, I’m not saying this approach can’t be made to work. Still, it’s difficult enough that some shops resort to spreadsheets and homegrown databases to track remnants, then waste valuable time trying to keep the ERP system synchronized.


To better manage dimensional inventory, SigmaMRP controls remnants of remnants of remnants with full traceability and no hassles.

Changing the rules

There is a better answer. “Our MRP engine knows everything there is to know about every piece of material in the shop,” says Valter Bonelli, director of product management at SigmaTek Systems LLC. “That means its dimensions and weight, but also its chemical composition, where it was purchased from, whether there are certs available, what jobs it was previously used on and when, and most importantly, its shape.”

This is a game changer for those manufacturing large numbers of sheet metal parts.


Because the software can tell you the exact shape of every remnant anywhere in the facility – that the piece of 1/4-in.-thick stainless sitting on rack A5 has a series of 2-in. holes running down the middle, or that the drop of 20-gauge aluminum that just came off the laser punch is T-shaped – it’s able to take this into consideration during nesting and more accurately plan material use based on those distinctive shapes.

Waste is eliminated – as is the panic that comes with last-minute purchase orders.

“In SigmaMRP, you can use a remnant of a remnant of a remnant with no loss of visibility anywhere in the process,” Bonelli says. “Maybe you have expensive materials where you want to get every last bit of value from each sheet or there are materials that you only use once in a while. For us, it’s not a problem. The shapes of each part and each skeleton are stored within the system and are taken into consideration during the planning and consumption processes.”


The user interface in SigmaMRP shows the status of every part on the shop floor, including its weight, costing information, preparation and production status, and quantity.

There’s more to this than improved material yield. Perhaps your programmer “overnests” his jobs, cutting more parts than are actually needed to avoid a material remnant. Or maybe the operator stacks those leftover sheets and oddball shapes behind the turret press because he knows they’ll get used at some point and picks through them every time a new job rolls around. These practices are not only wasteful, but create problems later on with material traceability and job costing.

Beyond planning, the software is easy to integrate. “In SigmaNest, we have complete integration with the most popular CAD systems, including SolidWorks, Autodesk Inventor, Siemens NX and so forth,” Bonelli points out. “That level of integration extends as well to our MRP function. So we can take a SolidWorks assembly through SigmaNest into SigmaMRP and if there’s a change to the part geometry at any time, it’s easy to push those changes through the entire system. It’s a huge timesaver.”

And what about the other aspects of ERP functionality? Bonelli says the SigmaTek suite of products covers everything from quoting and nesting to production and shipping.

“The only thing we don’t manage is finance, but we do tie into a number of common accounting packages,” he says. “Quite simply, our product is designed to address the unique needs of sheet metal manufacturers. That’s our core business, and we do it quite well.”

SigmaTek Systems LLC

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