December 11th, 2011 
Question by nines_rodriguez: Injection moulding assembly?
If these are the assembly spec:- Mould expense £2k. – Clamping-force 50 kN. – Width between necktie-bars 300 mm. – Melt force on introduction 20 MPa. – Shot perimeter 7 g. – Running cost £.01 /min. – Cycle clip 1 Min.And I neediness to do 750,000 small plastics discs (10 mm radius and 5 g mass), what is the disbursal per point when victimization the section assembly, if somebody could Archer me how to wash it putout it’d be a big assistance, cheer.oh and the assembly has a 2 baffle mould with single pit if that aid!All I’m precondition is what’s section, don’t advisement you demand to payoff thing else into relationship.
Best reply:
Answer by Toledo Engineer
You listed the run expense, which i would issue to expectation galvanism and annualized upkeep cost, but what about the others? Material disbursement? The Engineering Cost for design the component? Labor expense? Someone has to tally the assembly and sustenance it run. Someone has to apparatus the dice and return it run correctly.
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plasticinjectionmachine
The cycle time seems a bit too long, and you do not have the plastic material type or cost. Machine cost per hour of £.60 per hour seems low too. However from a technical perspective the machine seems adequate for the part described.
Scrap is also part of the cost. If the material is thermoplastic you can reuse the runner, if thermoset you cannot, in either case you need to know the runner weight.
If thermoplastic and a runner weight of 2.5 gms and a 2% scrap factor your material cost remains the same, but you must increase machine cost by 2% to cover the extra time required
If thermoset your part mass increases to 7.5 gm plus scrap or 7.65 gm and you must still add in the extra machine time for the 2% scrap factor
Here is how you do it:
Machine cost = cost per hour/pieces per hour.
With 1 cavity and a 60 second cycle pieces per hour=60
£.60/60=£.01
Add scrap and machine cost is.£.0102 per part
Material cost = Material cost per Kg/(pieces per Kg + scrap)
Assuming thermoplastic at £2/kg
£2/200=£.01 per part
Now you must amortize your mould cost
£2000/750,000 pieces=£.0027 per part
Now just sum the 3: .0102+.01+.0027=£.0229/part
You should also account for packaging, overhead, direct labour etc. for a true cost.