If the Part with Center with large opening for Audio Control Panel plug a great nos of Strengthening Ribs for warpage control and part Strength.

have the mold been build yet? product designer need to observe the rule to design rib thickness against the surface thickness. And mold maker need to consider the weldlines and possible sink marks position before cutting the mold, do a flow simulation with various gate position or use a diaphragm gate at the large openings to avoid weldlines.

Mold is not Built. Part design concept and outline with ribs locations indicated. Part thickness 3.5mm and rib ratio is 44%.Contemplate to core up or add material on potential sinkmark areas. Gating may have some constraint to certain areas.

The Part require High Gloss Finishing.

HI HH Yong,
We have rich experience mould maker and moulding shop in Asia, Indonesia, Singapore and China. we can help you to look at your product and tune to the cosmetic requirement. Are you looking for mould maker and mould for your product. If you can send us the product drawings we may be able to help and look into it. Like to know where you will be producing this parts.

To minimize the the sink mark, plastic material also play an important part, certain plastic has higher shrinkage factor then another, therefore also produce sink marks. Add material will cause more sink marks. 

We have the technology will eliminate ALL visible weld lines and improve sink marks.The process works by heating the surface of the mould (very quickly) to a temperature above the Glass Transition (Tg) temperature of an amorphous polymer (i.e. ABC, PC-ABS,ABS-PMMA, PC, PS etc) prior to injecting the hot plastic. This retards the formation of the "instantaneous frozen skin layer" that usually forms as the hot plastic comes into contact with the relatively cool surface of the steel mould.