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Moldflow economic benefits and improvement cases

Time：2024-10-16 08:28:44 / Popularity： / Source：

Moldflow analysis 
Analysis objectives:
1. Reduce product thickness from the current basic thickness of 3mm to 2.8mm, saving materials and costs.
2. Molding on a 1300-ton injection molding machine.
Other information:
Plastic material: Polystyrol 557 G (PS), BASF (USA)
Moldflow analysis 
Basic wall thickness of product: 3.0mm
Filling volume: 3656.82cm3
Moldflow analysis 
Three hot runners are poured in. Left picture shows filling situation.
From filling results, filling pattern is good and flow is balanced.
Moldflow analysis 
Maximum injection pressure during injection stage is 76.67MPa and maximum clamping force is 1300T.
Moldflow analysis 
Basic wall thickness of product: 2.8mm
Filling volume: 3413.04cm3
Moldflow analysis 
When product thickness is 2.8mm, if three-point pouring is used, short shots will occur in circled area.
Moldflow analysis 
When product thickness is 2.8mm, as shown above, three-point pouring will definitely result in short shots, so it is increased to four-point pouring.
As shown in left figure, filling flow is relatively balanced and there is no short shot phenomenon.
Moldflow analysis 
Maximum clamping force during injection stage is 1300T, which is within specified clamping force range. Maximum injection pressure is 74.64MPa.
After optimizing product wall thickness:
1. Product volume is reduced by 243.78cm3 and weight is reduced by 232.52g;
2. Four hot runners are used to ensure smooth filling of product;
3. Maximum clamping force is 1300T, which is within specified clamping force range;
4. There are several obvious weld lines on product, and exhaust in weld line area should be strengthened.
Moldflow analysis 
This product used to use PC, which requires a very high injection pressure. From Moldflow analysis results, it can be seen that among the three candidate materials, PBT requires the lowest injection pressure.
Moldflow analysis 
Under one gate condition, weight of product that meets requirements of injection molding machine is 203g (17% lower than before) when minimum thickness of PBT material is 1.8mm.
Moldflow analysis 
With 4 gates, thickness can be reduced to 1.2mm
More than 4 gates will not significantly reduce injection pressure
With 4 gates and a thickness of 1.2mm, weight of product is 135 grams (44% lower than before)
Moldflow analysis 
Gate solution, weld line in bulb hole
Obvious weld line after electroplating
Moldflow analysis
Add gate, change mold ejection direction
Maximum injection pressure 152MPa - to meet machine requirements
Moldflow analysis 
No weld line in bulb hole area
Moldflow analysis 
Quality
No weld line in bulb hole area
Cost saving
  Material Weight Product cost Evaluation
Before PC 244g USD0.42 Only mold cost increased
After PBT 135g USD0.16
Cost reduction 33% 44% 62% ＜10%
Product: Transparent headlight lens
Material: PC
Problem: Long molding cycle
Result: Shortened molding cycle
Moldflow analysisMoldflow analysisMoldflow analysis 
Moldflow analysis
Molding cycle is shortened by 10 seconds.
Injection molding machine costs 30 RMB/h, so 10 seconds can save 0.083 RMB.
100,000 Shots can earn 8,300 RMB, and 20 batches can save 166,000 RMB in profit.
Solving cracking problem--Korea Union Machinery Connector
Moldflow analysis 
There is a weld line in hinge area.
Rapid temperature drop.
High stress in hinge area.
Moldflow analysis 
Establish the best gate to avoid weld lines, avoid sudden temperature rise and high shear stress
Moldflow analysis 
Location of weld line depends on gate location.
For two gates, shear heat and shear stress at hinge are relatively high.
Moldflow analysis 
Avoid breakage at hinges, reduce scrap rate and make assembly easier.
Previous (3 gates) Scrap Scrap rate (%)
New design (4 gates) 73/500 14.6
  17/500 3.4
Product: Cylinder head
Material: PA66+20%
Main problem: Low weld line strength, easy product breakage, high scrap rate (12.2%)
Solution: Local wall thickness adjustment to optimize flow pattern
Moldflow analysis 
Weld lines and trapped air.
Air trapped at melting front causes low weld line strength.
Moldflow analysisMoldflow analysis 
After thickness changes, collision angle of weld line increases.
Gas is easily discharged without trapped gas.
Moldflow analysis 
Product quality
Deformation in Z direction reduced by 20%
Improved weld line strength, no air entrapment, no breakage.
Cost savings
Increase in product weight: 36 g/piece, increase of €1,500
Reduction in scrap rate: 12.2% → 0%, saving of €60,000
Savings of €58,500 (40,000 products) from scrap reduction alone
Last article：Effect of pouring temperature on microstructure evolution and properties of die-cast Al-10Si-0.3Mg a Next article：A brief introduction to die casting process

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