High Pressure Injection Molding

How much clamp tonnage does my part need?

Clamp tonnage is set by the part’s projected area, which is the shadow the part casts looking straight into the mold, not its surface area or its weight. A common starting estimate is 2 to 5 tons of clamp force per square inch of projected area, with lower-flow resins like polycarbonate and nylon at the top of that range, and a multi-cavity tool multiplying the total. 20/20 Custom Molded Plastics confirms press size against your actual geometry before tooling is committed.

What limits how large a high-pressure molded part can be?

Three specs set the ceiling. Clamp tonnage limits the part’s projected area, shot capacity limits how much plastic can be injected in one cycle, and the spacing between the press tie bars limits the physical size of the mold. A part can clear one of these and fail another, so 20/20 checks all three against a specific press before quoting.

What tolerances can high-pressure injection molding hold?

High-pressure molding packs plastic into the tool under heavy force, so it holds tighter and more repeatable tolerances than low-pressure processes. What is achievable on a given part depends on the resin’s shrink rate, the size of the dimension, and the tool itself. Larger dimensions carry wider tolerances because shrinkage accumulates across the part. Call out only the dimensions that are critical to fit or function, since blanket tight tolerances raise tooling cost without improving how the part performs.

Why does high-pressure molding require steel tooling?

The tool has to survive repeated cycles under heavy injection and clamp pressure without deflecting, and aluminum will not hold up to that on a production run. Steel costs more upfront and takes longer to cut, so on a new high-pressure program the tooling decision usually sets the schedule. Low-pressure structural foam is the process where aluminum tooling becomes practical.

Can 20/20 quote the same part in both high pressure and structural foam?

Yes. 20/20 Custom Molded Plastics runs high-pressure injection molding alongside low-pressure structural foam, structural web, and gas assist, with the high-pressure plant sitting next to the low-pressure plant on the Holiday City, Ohio campus. A part that sits near the line on size, wall thickness, or finish can be looked at both ways before tooling is committed, which is the point where the decision is still cheap to change.

What do you need to quote a high-pressure part?

A 3D model or part print is the starting point. Quotes move fastest when they also include annual volume, the resin or the performance the part has to meet, which dimensions are critical, any assembly or finishing required, and whether tooling already exists. 20/20 reviews the geometry, flags anything that will cause trouble in the mold, and returns a molding estimate.