Blow-Molded Mold Maintenance

Blow-Molded Mold Maintenance

The Life of A Blow-Molded Product Mold

If you were preparing to drive cross country, chances are you’d schedule an inspection of your car well before you and your GPS (or maps) hit the road. The same rule of thumb applies to manufacturing a molded product.

Well before your manufacturer of choice schedules your “trip” (production run), they should conduct a thorough inspection of your “vehicle” (mold). The last thing you want is to have to explain to customers, salespeople, or channel partners that you encountered an unexpected breakdown halfway through your journey.

The life of a mold depends on the age of the mold and the numbers of products it has produced. According to Richard Bell, our Tooling Manager, “A well-maintained blow mold should last 15 - 20 years before the materials begin to fail beyond repair.”

However, the shortest life of a mold Richard has seen in his career (he worked for a mold builder before joining the Apex team) was about one year. That mold was used 24/7, 365 days a year!

Standard mold maintenance involves the inspection of three main areas:

  • Sandblasting and preparation of the cavity.

Sandblasting of the mold gives a roughness to the surface. This helps with venting when the bottle is made and gives the product a matte finish – no shiny spots.

  • The parting line.

This is the place where the two mold halves meet. The parting line should be a square and matched edge. This minimizes the raised line – known as the witness line  – that you see on the finished product.

  • Pins and bushings.

These parts keep the parting line from going off center. If the line is off center, you’ll see a ridge up the side of the product. (The next time you’re in a supermarket, start examining bottles!)

A mold should be inspected prior to every production run. A typical inspection at Apex Plastics takes 30 minutes. Additional time may be required if the inspection results in items to address.

Some manufacturers make and/or repair molds in house. Others rely on mold builders to make and repair molds. However your supplier of choice operates, be sure to have a conversation up front about how your product mold will be maintained.

If you have questions about a mold you own or need to create, let us know.