The weakest link in fabrication often is made of paper

Thanks to e-mails and electronic documents, offices tend to be tree-friendly these days. The shop floor is another matter, as paper-based documents regularly are used to track jobs.

Material needs to be tracked from delivery to the stockroom and out on the shop floor, with any remaining material being booked back into stock. Assemblies also need to be taken into consideration. While material requirements planning (MRP) often manages this material tracking, some systems do not cover the design and manufacturing processes; this is where an intermediate solution is required. For ordering purposes, it helps if the bill of materials (BOM) can be imported from a CAD or MRP system and used to plan assembly fabrication and nesting.

With nesting, one of sheet metal fabricating’s unique requirements, several orders can be combined on one sheet, or a single order can be spread across different materials or thicknesses. Existing CAM and nesting software systems must be fed with order, material, and part information to generate nests. Once this information has been processed, the loop needs to be closed with information on parts completed and parts scrapped fed back to the MRP system. This enables the MRP system to close the work order for that part and update the estimated machine time with the actual processing time. This information helps the MRP system cost future jobs more accurately.

So, if all of these software systems exist, where is the problem? MRP systems do not follow every journey in its entirety; often do not interface with specialty systems, such as nesting software; and rely on much more human intervention than is often necessary.

Order Management

An MRP system generates a work order, usually paper-based, which follows a job through the factory. When an order gets to the design office, its information must be entered in a CAM system, so that geometry files can be created or located and then nested. This data entry process often is manual and error-prone and provides no visible feedback to other departments of the work order’s current status. Prioritizing or grouping orders generally is done outside of MRP and again falls outside of management view. A list of all orders also may need to be broken down by manufacturing cell, creating sublists on a per-day or per-machine basis, for example.

Material Management

Sheet metal management also has unique challenges. While MRP software can manage your stockroom, tracking the material on the shop floor and managing remnant sheets often falls outside of its domain, leaving paper-based systems or home-grown Excel spreadsheets to fill the gap.

Some companies that cut low-cost material may think it’s cheaper in the short term to scrap considerable amounts of stock rather than task staff with managing the remnants. However, over the long term this policy equals a larger loss. The only successful way to track this shop floor and remnant material is to link tracking software to the nesting system. Then, when a nest is generated, information on the remaining material is available, and this material can be logged alongside new stock. With such a system in place, shops can make intelligent decisions automatically for future nests in which the remnant sheet may be used instead of new stock.

Nesting

Shops run static nests, dynamic nests, or a mixture of the two. Static nests are highly optimized nests of components that often are produced many times, whereas dynamic nests are generated each time for the specified components. Unless a highly efficient nesting system is in place, dynamic nests invariably are less efficient than static nests.

Many shops that cut expensive material use only static nesting software because of the perception that dynamic nesting systems aren’t fast or efficient. This perception is no longer true. Newer order and nest management systems allow users to create dynamic nests and still use static nests. The system highlights a suitable static nest from the nest database for any given order mix. The programmer can still decide to run a new nest and then compare the results. If the new nest is more efficient, he can select to replace the existing static nest with the new one.

By the time jobs reach the shop floor for manufacturing, the information the machine operator requires may differ significantly from the data on the work order generated by the MRP software. The operator simply wants to see which nests he needs to run and in what order; he then has to allocate the right parts for each order once the nest has been cut. Wading through reams of paper with possible errors and duplicate entries is inefficient and can cause longer lead-times, poor purchasing decisions, and an overall waste of resources.

Pinpointing  Bottlenecks With the Bigger View in Mind

Bottlenecks invariably occur when automation stops and workers are required to take action. Some processes cannot be fully automated, for example, taking delivery of stock, but they often can be simplified. Bar code and radio frequency identification (RFID) stations on the shop floor reduce data entry errors while providing a faster work flow and live feedback of an order’s status.

A phrase often used in software interface design is also relevant when evaluating work flow processes – K.I.S.S. – Keep It Simple, Stupid! Work flow procedures in any business generally are borne from the mistakes of yesteryear and can be overcompensations for problems that no longer exist. When human interaction is required, existing data should be used whenever possible rather than re-entering it, and the method used to input data should be as simple as possible. Finally, only relevant data should be displayed for any given task.

While each of these fabrication links can be managed with its own stand-alone system, they all are linked to each other, so it is logical to look for software that can encompass material tracking, remnant management, order tracking, and nest scheduling. All of these elements are relational and rely on common data.

Data integrity is fundamental in delivering visibility. Get the data input right and it is there to be mined any way you want it. Reporting becomes easier; in fact, paper-based reports diminish in importance if the information is there live, on-screen, in front of you. While paper may never be banished from the shop floor completely, you can do a great deal to minimize your reliance on it.