Short-Run Machining and Molding: The Work Your Line Isn't Set Up For

It is easy to think of a short run as a small version of a long one: the same work, fewer parts, a smaller invoice. For a production molder or a high-volume machine shop it is closer to the opposite. Most of the cost of a run sits in getting started, and a short run pays all of that start-up cost for very few parts.

So a short run is expensive for a line built for volume, and ordinary for a shop built around setup. That is why short runs, pilot batches and service parts tend to wait at the back of a busy molder's queue, and why they often end up somewhere else.

Between 2020 and 2025 the shop made molds, short runs and repairs for other manufacturers, including plastics molders. It also made molded and machined parts for automotive suppliers, and molded and machined parts and fixtures for electronics manufacturers. Its molding runs went from tens of parts to tens of thousands.

What a short run costs a production molder

On an injection molding press, making the parts is the quick part. Before the first good part, the mold has to be hung in the press and its water lines connected. Many resins have to be dried for hours first, or the parts come out brittle or streaked. The barrel has to be purged of the last job's material. The first parts have to be checked and approved. After the run, the mold comes out again and the press is set up for the next job.

On a long run, all of that disappears into the cost of each part. On a run of a few hundred, it can cost more than the parts themselves.

There is a quality reason too. A small mold on a big press uses only a small share of the barrel on each shot. The plastic then sits hot in the barrel longer than it should, and some resins degrade, which shows up as discoloured or weak parts. A press sized to the mold avoids that.

Machining has the same shape. Proving out a program and checking the first part take about the same time whether the order is five parts or five thousand.

What we take on

• Short machining runs in most metals and engineering plastics
• Short molding runs on aluminum or steel molds we build and run in our own shop
• Pilot and pre-production batches, including on bridge tooling while production tooling is still being made
• Replacement and service parts for products out of regular production
• Overflow when your own capacity is full

Our quotes price setup separately from each part. how we quote setup and parts, and why there is no minimum order explains the method.

Our presses are 60-ton and 150-ton, and we run molds clients already own as well as molds we build. Common mold sizes we work with are about 8 x 8 and 9 x 16 inches. We can make steel molds, and we'll tell you if one of our partner shops is better suited.

Who owns what

On short runs, ownership is a question buyers are right to ask early. You own the tool and the production CAD once you have paid for them. Fixtures we design and build for you are yours once paid for. The shop's own workholding, methods and process knowledge stay ours.

When a short run isn't the answer

If your run is long and steady, a production molder will beat us on the price of each part, and it should. when to move from a short-run shop to a production molder sets out the signals.

If you have a run that keeps sliding down your own schedule, send the drawing or model, the material, the quantities now and later, and whether a mold for it already exists.

Related services: Aluminum tooling, molding and machined parts Shop capabilities