Business Issues

1
Business Issues

• Of Vacuum Assisted Casting

2
Cost determinants

• Cost of silicone gel
• Cost of PU resin
• Shelf life of PU resin
• Life of silicone mould
• Labour cost
• Pattern cost
• Post-processing cost

3
Cost of silicone gel

• The pricing unit of silicone gel is usually Kg
• The price varies from
• Low end opaque gel KE12 92/Kg
• High-end transparent gel KE1300T 230/Kg
• Typically 1 Kg of gel can cast a block of 1L

4
Cost of PU resin

• The pricing unit of PU resin is Kg
• The price varies from
• Low end 300A/B 270/2Kg
• High end 2020 900/3Kg
• The weight of PU duplicate is about the same as
  injection moulded part

5
Shelf life of PU resin

• Once unsealed, PU resin will absorb moisture from
  the environment
• To prolong the shelf life, resin should be stored
  at around 50C
• The resin quality degrade noticeably after 1 week
• Most resin will be un-usable after 6 months

6
Life of silicone mould

• Silicone mould is inert to elements, the shelf
  life of mould is measured in years
• PU resins are very corrosive, silicone mould can
  withstand the resin attack up to 5 6 cycle
• Hardening and cracks will start to develop when
  over 10 cycles
• Accuracy, surface quality will deteriorate,
  flushes will be more visible

7
Labour cost

• PU duplication requires 3 skill sets
• Project management, costing, scheduling
• Mould design, including parting design, mould
  splitting, and gating
• PU casting, pre and post processing
• In PRD, usually a Master is responsible for 1
  2, and an apprentice is responsible for 3

8
Pattern cost

• Least important among the factors
• In many cases the pattern will be one of the
  deliverables
• Usually a duplication job us the pattern provided
  as is, it will not include any polishing /
  surface refinement

9
Post-processing cost

• Good mould design can highly reduce
  post-processing workload
• If mould quality is bad or the mould is used for
  too many time, the cast part may need some sanding

10
Time factor

• If the job is urgent, or the PU used is very
  slow-curing, one may
• Work overtime
• Make more than one set of mould
• Make more than one cavity in a mould (need more
  pattern, but if the pattern can be counted as one
  deliverable it will be less costly)