Blow molding can make shooting hoops against LeBron James look easy. Blow molding consultants like to describe it as the most technically challenging of the molding processes, and they’re probably not wrong. Why? Because in the blow molding world, having a perfect mold isn’t enough — that mold can still make an unaccept-able part if the molder isn’t in total control of the entire process, including the many indirectly controlled vari-ables. Simply put, the blow molding process itself exerts a major influence on the end product.
Which is why it’s crucial for the machinery makers to keep improving their equipment and technologies. With that in mind, here’s a look at some of the latest developments in extrusion blow molding, injection blow molding, stretch blow molding, and automation.
Amsler Equipment Inc. has rede-signed its four-cavity, linear stretch blow molding machine for PET. Like its predecessor, the L42, Amsler’s new L42X can blow bottles up to two liters in size using four cavities, and bottles up to five liters in two cavities; but in the new machine, the maximum neck diameter is 63 mm, compared to 48 mm in the prior version. Improved features include upgraded drives, heating lamps, oven controls, and control software and hardware. Additionally, all machine motions now are servo-controlled, giving the operator a better handle on all motions within the machine, including rotation of preforms through the oven. The L42X individually controls the heating of the four preforms before they’re moved into the molding area. The clamp is double-acting, so that both mold halves move away from the centreline upon opening; clamp compensation acts on both sides of the mold. Designed for producing packaging especially canisters the new Eblow 37 hybrid blow molding machine from Bekum Machinenfabricken GmbH is based on the company’s hydraulic BA 34.2 units. The Eblow 37’s closing unit and mold closing functions are electrically driven, though a servo-hydraulic system handles closing pressure buildup. The machine has a closing pressure of about 42 tons and a mold width of 700 mm. The Eblow 37 boosts canister production by up to 15 per cent over comparable hydraulic systems, Bekum said, and can produce 240 canisters per hour. With its spiral distributor blow heads, the machine is designed for easy material changeovers and maintenance. It can handle both single- and multiple-layer structures.
New to the blow molding business, Dr. Boy GmbH & Co., the German parent of Boy Machines Inc., has introduced an injection blow molding system that utilizes a Boy 60 E horizontal injection press with a four-cavity, hot runner mold with an index plate that rotates 180° to transfer injection molded preforms to the blowing station. At the K 2016 trade show in Germany last year, the system produced eyedropper bottles that were dropped onto a conveyor belt for immediate packaging. Using a manifold system developed specifically for that application, the preforms were injected without sprues, so that no waste was produced in bottle production. And unlike with traditional blow molds, the bottle was finished at the end of the blowing process, with no material used to seal the mold body needing to be cut and removed.