What to Expect When You Order a Mold: The Pilot Run and Mold Modification Process

The First Shots (T1 Samples)

After several weeks of mold design and fabrication, we will conduct the first trial run. The initial parts from this run are called “T1 samples.” This is your first opportunity to hold a real part produced from your production tool.

When you receive your T1 samples, your job is to perform a thorough review. At this stage, you should focus on:

• Fit and Form: Does the part have the correct dimensions?
• Assembly: Does it assemble correctly with its mating parts?
• Function: Do the snap-fits engage properly? Do the moving parts work as intended?

Don't worry about color or surface texture at this stage. T1s are typically run in a natural, uncolored resin, and the final texture is often not applied to the mold until after the part geometry is fully approved.

Making Mold Modifications: The “Steel Safe” Rule

What if something isn't quite right? A snap is too loose, or a clearance is too tight. This is when we discuss mold modifications. When making changes, we are always guided by one simple but critical rule: it is easy to remove steel from a mold, but it is very difficult and expensive to add it back.

This gives rise to the term “steel safe.”

• A “steel safe” change is one where you want to add plastic to your part. To do this, we simply machine away more steel from the mold cavity. This is a relatively straightforward and low-cost modification.
• A non-“steel safe” change is one where you want to remove plastic from your part. This requires us to add steel to the mold, which involves precision micro-welding and then re-machining the surface. This process is complex, costly, and not always possible.

Because of this, it's always best practice to design features like press-fits or tight clearances to be “steel safe”—meaning, design them a little tight, with the expectation that we can easily open up the tolerance by removing a tiny amount of steel if needed.

Your Partner in Production

From initial design review to final part approval, our job is to be your expert partner. We help you navigate these final steps to ensure the part you designed is the part you receive, every single time.

This concludes our introductory series on designing for injection molding. If you're ready to put these principles into practice, our team in Johor Bahru is here to help turn your design into a world-class product. Contact us today to start the conversation.