Notes from the Road 5

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Notes from the Road…5

(RotoWorld Magazine, September-October 2008 Volume IV, Issue 5)

Release Me

How long can you mold between coatings of release agent? 1 part, 1 shift, 1 day, 1 month, 1 year? Blooming sticking – no I’m not swearing at you, these are just two of the common problems associated with release. Add to that warpage and surface contamination and you have an insight into the somewhat mysterious world of release agents. More than a few molders operate essentially with little or no release agent and are confused as to why others suffer sticking problems. So how can they do this? Often they don’t know themselves, but some of the factors involved include: waxes or lubricants in the raw material (sometimes added during compounding), mold material and surface finish, relatively low molding temperatures, residues and excess pigment from dry-blended materials and part design. While the range of coatings from which molders can choose is wide (water based, solvent based, silicone grease, silicone spray, semi-permanent, TeflonTM coating, high temperature paint coatings, galvanic coatings) the complete picture of the interaction between molding parameters and release agents does not appear to be fully understood (or at least published). Project anyone?  

Wind, Waves & Water

Rotomolding certainly has an affinity for water as showcased by the very successful conference held in Belfast , Northern Ireland by the ARMO group last month. And in keeping with that theme, new parts for rotomolding related to water seem to keep popping up everywhere from West Africa to Dubai to Kentucky . They include all sorts of boats (from electric to fishing boats – currently up to 24ft (7.3m) long but planning for 28ft (8.5m)), flood and protection barriers (both on-land and at sea), breakers (for erosion and security control), water processing/recovery systems (as water regulations tighten, areas such as Scandinavia have spawned a huge interest in water reprocessing) and sewage treatment components (manholes, connection chambers and even piping have embraced the flexibility and toughness of rotomolded parts). Security and resource management are clearly two key global themes worth exploring.

The Perfect CycleTM

What’s your definition of the Perfect Cycle? Super fast heating? Super fast cooling both inside and outside the part? Fast melting material? How about simply a cycle that generates income? The Perfect Cycle should be one that generates profit for your organization and is likely to be different from part-to-part and from molder-to-molder. The needs of different markets and the pressures of material pricing and energy costs will also affect how molders approach creating their Perfect Cycles.

At its most basic level, many molders can achieve perfection with an open flame machine, recycled powder, hand-made sheet metal molds and a ready market for simple water tanks. This can be perfectly acceptable in a given market. However, as molders become more sophisticated, they will start to incorporate elements of proven technology that already exists in rotomolding (temperature control systems, multiple layers, foaming, internal pressure, optimized cure, internal cooling, MIG RMC3, Maus-holes, Supa-Vents, Mold-Jacks, etc.). Ultimately molders at the highest level must integrate product design, material selection, process control and product testing to achieve the highest quality; they will push the limits of the process somehow in terms of speed, aesthetics or performance.

As molders perfect their operations, suppliers are also trying to perfect materials, molds and machines. New additives are available for potentially speeding up both the heating and cooling cycles; mold features which concentrate on maintaining a clean and protected parting line help improve part quality and mold longevity; fully automatic machinery is now available in the form of Leonardo, eliminating our process dependence on the human element, improving direct controls of all aspects of the process while reducing operating costs.

Do you operate with a Perfect Cycle for any of your parts? Choosing the tools and technology best suited to finding the Perfect Cycle for your required degree of molding will depend on a combination of profitability, how critical the specifications for your product are and how far you are willing to push the limits of the process. Good luck in your search.

Training in Reality

Rotomolders work in a wide variety of markets and while they share a common process (or in some cases elements of the process) there is often little in common between the business models that they operate. However, and while this may sound like a broken record, it doesn’t matter if they are in Africa, Asia, Australia or Ballybucklebo, there are a set of common issues which every rotomolder should address and should make sure that their people understand. These include four basic areas: material preparation, mold release, venting and part inspection. When molders focus on training their people in these areas and make sure that everyone understands the relationships between them, many of the most common rotomolding problems are reduced or eliminated. They are not complicated in principle (although release can be a mystery at times) but they do need to be formalized and discussed in teams so that people adopt a companywide approach rather than their own personal approaches. Quick test: how many of your operators understand the basic relationship between powder quality and finish of their parts?

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Last modified: October 31, 2008