Injection-Molding

Injection molding machines are workhorses of the plastics industry. Every machine has tie bars, plasticizing barrels, and platens that require deep hole drilling. These components operate under high pressure and cyclic loading, so the bore quality directly affects machine reliability. I have drilled injection molding machine components for several OEMs over the years. The parts range from 2-meter tie bars to 4-meter plasticizing barrels with complex internal geometries. Tie bars in particular share similarities with general long shaft deep hole drilling but with specific requirements for hydraulic oil passage bores. ...

Injection molding machine platens are large steel blocks that hold the mold halves. The moving platen slides on the tie bars through precision-drilled holes. The platens also need drilled cooling channels for temperature control. In my experience, the tie bar hole accuracy determines whether the injection molding machine produces consistent parts over millions of cycles. Platen Sizes and Material Specifications A platen for a large injection molding machine can be 1-3 meters wide and 30-60cm thick. The tie bar holes are 80-200mm diameter through the full platen thickness. The position tolerance between the four tie bar holes is typically within 0.1mm. ...

Injection molding machine tie bars are long, heavy-duty rods that guide the moving platen and carry the clamping force. Some tie bars need a through-hole for the clamping mechanism or for lubrication. In my experience, the through-hole concentricity is the single most critical factor determining whether the tie bar performs reliably over years of cycling. Tie Bar Specifications and Material Properties A typical tie bar is 2-5 meters long with a 20-50mm through-hole. The material is high-strength steel like 42CrMo4, often induction-hardened on the OD. The drilling is done before hardening because the hardened surface is too tough for efficient drilling. ...