Orthotic PU injection foam insoles

20 years ago PU foam, shaped insoles were not available. The only choices were EVA & Polyolefin foams and flat PU foam sheet. We were approached by a Melbourne based footwear manufacturer to develop a shaped PU foam version. PU foam being microcellular will hold its shape and stay supportive whereas EVA & PO foams lose their shape within days in use.

The foam used was developed by AXIAM and ERA Technicians specifically for this range of products. Further improvements are continuously being researched and developed and we expect to be moving to our new material soon which will give improved wear and lighter weight along with being a fully water vapour blown system in line with AXIAM’s environmental strategies.

After developing and establishing sound manufacturing processes and materials, We later began working with two Australian based podiatrists who wished to develop their own range of Orthotic insoles with various angle arch supports and heel supports, something that previously was often hand made by a podiatrist. This required taking it to a whole new level in many ways. These needed to be made with accurate and consistent hardness and shape as well as developing the range to be as aesthetically pleasing to the consumer as they are practical.

A large range of products are now made with various coverings, Poron, Tailex, Bovine Suede, Kangaroo leather, silverline, possum skin, Texon Board and even automotive fabric that are off cuts of waste fabric used for our Ford project, recycling that waste where ever possible.

Some products require stickers and/or heat transfer logos which is also applied in house. Packaging requirements vary considerably from zip lock poly bags with slip cards, to blister packs for point of sale national and international markets.

Materials used and continuously developed for this product and process specifically target the following key requirements:

• Cost to market.
• Good process ability to reduce waste and cost.
• Memory to ensure shape is held.
• Softness and the ability to ensure its consistency.
• End of life properties
• Environmentally friendly processing using water blown systems. i.e. No CFC’s.

Machinery for processing these products needed to be developed. Reconditioning and modifying old PU injection heads that had long been obsolete, and design & build of pneumatic driven 12 station rotary tables that could accommodate our in house made moulds mounted vertically.

The filling of the closed mould is done under low pressure, the remaining air needs to be expelled without causing air entrapment bubbles for this purpose the gate needs to remain open until creaming begins and allow some of the reacting foam back out the gate once the injecting nozzle is pulled away, the gate must then be closed at a precise moment to allow pressure to build up inside the mould cavity to fully form the moulded part.

This is done by pneumatic shut offs as part of the tooling on each individual unit. Timing of this is critical in ensuring density and hardness is consistent and correct.

Almost 250,000 units sold last year with approximately 90% exported to Australia & UK, new market opportunities are currently being explored in the USA & Canada

Marketing is controlled by our customers but we help by running a supermarket warehouse for them where we make and stock against forecast sales, orders are sent overnight to shipping hubs for export. All tooling manufacture and design has was done in house, All packaging provided by NZ based suppliers.

A move instigated by AXIAM Plastics and encouraged by price incentive is to replace blister packs with biodegradable printed zip lock poly bags. This not only helps us with storage space but also saves in shipping costs as we can get more into a carton and naturally when discarded will take up less space in landfill and eventually breakdown.

PU foam is inherently biodegradable; it is broken down by both bacterial microbes and hydrolysis. In warm humid conditions this can be rapid.

Along with our supplier and a years development, a new foam system was formulated. This was very difficult as chemically blown systems tend to perform much better. The main reason to reformulate was to reduce environmental impact, especially Ozone depletion. We are now running the improved water vapour blown system. All the coverings are also biodegradable.

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