Difference Between

Specific decisions for the best approach (material, process, design detailing) can only be made with a detailed knowledge of all the constraints (structural, dimensional and financial) and all the must-have, nice-to-have and absolute must-not-have features and attributes. Is there not a web address where we can get more detailed information? Another process (actually, a hybrid process) came to mind and this might suit the combination of requirements that I think you have. This is offered by a couple of machine manufacturers. You'd need to contact the machinery manufacturers direct for contact details of processors offering this service. A thin skin (can be vacuum-formed) is normally inserted in the relatively low-cost mold, to give high-quality surface. The robotic head dispenses PUR foam with reinforcing fibers - that are chopped in the head also - into the open mold. Once the mold is closed, the "B" surface is formed, complete with any ribbing and fixing points, etc. However, the total thickness will tend to be significantly well above the 5mm maximum that you have defined. Rigidity is very impressive. Impact strength will depend on surface material and density/reinforcement variables in the backing material.

When using compression molding the cavity is slightly open when injecting and thus has more room for material. This way all the needed material can be injected rapidly into the cavity and instead of applying pressure in the material the mold clamps and thereby closes the cavity to the intended size (or volume). This reduces the internal stress in the part as you can image the molecules finding their own space so to say. Compression molding is very useful in thin wall parts to better be able to fill the part during injection and optical parts where stress will disturb the optical quality of the part, that's the pros.

However many beverage caps use continuous rotary compression molding which is altogether a different process. We used this process at a company I worked at for 35mm film cans and covers and it can be hypnotic to watch it run at full speed. If you look at a beverage cap and there is no indication of a gate mark on the part, it was most likely compression molded.

You can get a larger shot size out of a hydraulic injection molding machine. There are times when you are pushing the injection capacity of the injection unit that hydraulic machines are a better choice than all-electric injection molding machines. However, if the job is within the range of the injection unit and specified properly, the electric machines outperform hydraulic for repeatability and energy consumption.

The main consideration when considering an all-electric injection molding machine is energy efficiency. Electricity savings of 20%-40% are typical when compared to hydraulic machines. Also, an all-electric machine can offer unmatched repeatability due to the servo drives that are used for injection forward and clamp rather than hydraulic pumps/valves.

Soft tool is the tool made of pre-harden steel, it is an economic solution for a small volume production. It has advantages of low cost and fast turn around, but pre-harden steel is a lower grades steel that process lower hardness and wear resistance, so the soft tool can only stand molding cycles no more than 500k shots, it's also difficult to maintain tight tolerances.

Hard tool is a high quality tooling for mass production, it's made of the best quality steel, like H13,420 etc. Hard tool requires more procedure and longer time to manufacture.