After 10 years of product structure design, from consumer electronics to medical devices,
I have stepped on countless pits. Today, I sorted out 8 core experiences,
I hope I can help friends who are doing or preparing to enter the industry to avoid detours.

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1️⃣Look at the process before the design

Many newcomers get the ID picture and start to do it, making a lot of pictures,
Results One assessment found that mass production was not possible at all.

▪The first step to get the plan: confirm the forming method (injection molding/die casting/CNC/sheet metal)
▪The injection molded parts give priority to the demoulding direction to avoid a large number of side core pulling.
▪The basic rules of wall thickness, draft angle and reinforcement should be set before modeling.

💡The formula: first think about how to make it, then think about how to draw it well.

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2️⃣Buckle is not the more the better

In the early days, I was always worried that the assembly was not firm and I added buckles everywhere.
As a result, the mold is complex, difficult to assemble, and prone to stress concentration.

✅Correct approach:
▪2-3 main positioning buckles and several auxiliary buckles are sufficient
▪The buckle cantilever shall have enough deformation space (deflection ≥ 0.5mm)
▪The amount of inverted buckle depends on the material: ABS 0.8-1.2mm,PP can be appropriately increased

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3️⃣The stop is more important than the appearance

The stop (Step) is the key detail that determines the delicacy of the product.

▪Coordination of upper and lower shells: 0.3-0.5mm segment difference is recommended to avoid white exposure.
▪The internal and external stops are used together, which is beautiful and dustproof.
▪The direction of the stop should consider the assembly sequence, don't fail to install it.

📌The "cheap feeling" of many products comes from the lack of stop treatment.

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4️⃣Screw column is a door knowledge

Seemingly simple screw column, do a good job to save costs, do not be a disaster.

▪️ Screw post outer diameter = thread diameter × 2 (minimum)
▪Reinforcing ribs (at least 3 uniform) must be added to prevent cracking when screwing
▪️Through holes are better than blind holes, which are convenient for tapping and guiding
▪Avoid important exterior surfaces, screw holes can be hidden

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5️⃣Leave enough tolerance, don't pursue theoretical perfection.

The 0.01mm accuracy on the drawing is meaningless in the world of injection molding.

▪General plastic tolerance 0.1-0.2mm is enough
▪The matching parts should be reserved for clearance, and the interference fit should be cautious.
▪Critical dimension tolerance, non-critical dimension free tolerance can be

⚠The pursuit of unnecessary accuracy will only increase costs and scrap rates.

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6️⃣Mold consciousness should be established from the first day

A structural engineer who does not look at the mold is incomplete.

▪In the design stage, the position of the parting line should be considered, and the parting line should not be cut to the appearance surface.
▪Try to avoid reversing, one side core pulling may increase tens of thousands of mold fees.
▪Understand the position of the thimble to avoid the top mark affecting the appearance
▪Communicate more with mold factories, their feedback is more useful than books.

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7️⃣Heat dissipation and waterproofing are often overlooked

Especially electronic products and medical devices, these two points are crucial.

▪Heat dissipation: convection channels should be reserved in enclosed spaces, and airtight should be avoided near heating elements.
▪Waterproof: IP grade determines the sealing method, and the sealing groove rubber ring should be considered above IPX4
▪Battery compartment should consider heat dissipation and safety protection separately

🏥Medical devices in this regard more stringent requirements, compliance must be pre-consideration.

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8️⃣The trial is not the end, it is just the beginning.

T0 model test is only the starting point to verify the feasibility, there is still a long way to go:

▪T0 key points: whether the size is qualified, whether the assembly is smooth, and whether there are obvious defects
▪T1-T3: mold repair optimization, surface treatment adjustment, assembly tolerance fine adjustment
▪Small batch trial production must be done before mass production, and problems found should be corrected in time.

💡Record the problems and solutions of each test model,
These experiences are your most valuable assets.

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Written at the end:

In this line of structural design, it is easy to get started and difficult to master.
The first 3 years is the accumulation period, 5-8 years began to feel,
It will take more than 10 years to really say "understand".

If you encounter specific problems in the process of structural design,
Welcome to exchange in the comment area and discuss and solve the problem together.👇

# Structural Design# Product Design# Industrial Design# Mass Production Design# Medical Device Design
# Design Experience# Mold# Injection Design