Should acceptance of a case injection molding machine include destructive testing?

Answer: Yes, on one part only. Hold 60 kg static for 24 hours against 0.5 mm of flatness change, and drop from 1.2 m onto six faces once a quarter.

Can a cavity 0.3 mm out be taken on concession?

Answer: Check the assembly. Oversize with the gasket still at 25 percent compression can pass one batch; undersize cannot, because the liner will not enter.

What wins when the trial report and the standard disagree?

Answer: The drawing, then the signed sample. A trial report records a process; it never replaces a pass line.

Does a material change force fresh acceptance?

Answer: Yes. Polypropylene against polyamide differs by 0.8 percent shrinkage, which moves a cavity 0.4 mm, so 3 first-offs and 30 shots are repeated.

A 40,000 yuan mistake: case injection molding machine sign-off

Quick answer: Acceptance rests on three documents, four fixed measuring habits and three disposal routes. Write the pass line as a number, the disposal as money and days, and nothing is left to argue about.

Three documents behind every acceptance call
Four measuring habits at the goods-in gate
Dimensions and shot weight: which side of the tolerance
Cycle and appearance: pace, weld lines, colour
Repair, concession or return
Writing the record so blame can be traced
FAQ

1. Three documents behind every acceptance call

A 480 piece batch was passed last year on a concession note. Three months later 37 split at the base of the latch, the claim ran half a year, and both sides paid half. The sheet carried four words in the verdict column: appearance acceptable.

The inspector was not careless; the criteria were never pinned down. Three documents hold a case injection molding machine to account: the drawing for dimensions, the trial report for the process window, the receiving standard for sampling. Where they disagree the drawing wins, then the signed sample.

Document	Covers	Usual gap
Drawing	520 by 380 by 200 mm cavity, 3.2 mm wall, 0.25 mm tolerance	No datum face on key dimensions
Trial report	3 first-offs, readings and settings	Says pass, omits readings
Receiving standard	Sample size, pass line, disposal	No disposal clause

Sampling follows GB/T 2828.1 and dimensional grades follow GB/T 14486, but the numbers on the sheet come from the drawing; a standard settles method, never your tolerance.

2. Four measuring habits at the goods-in gate

Disputes at goods-in are rarely instrument error, they are habits that differ by shift. One case reads 519.8 mm before lunch and 520.4 mm after, and 0.6 mm justifies two opposite verdicts.

Case Injection Molding Machine output: matte translucent case face-on, two round holes inside the handle, three black feet

Rest the part 2 hours at 23 degrees, because a case off the tool still carries 60 and reads 0.3 mm small. Take three readings and keep the largest, since corners shrink differently. Blow flash off before weighing; a 0.15 mm sliver adds 4 g. Average the cycle over 10 shots.

Item	Instrument	Rule
Cavity length, width, depth	Calliper, 0.02 mm	Three readings, 8 mm off corners
Part weight	Scale, 0.5 g	Air-clean flash, weigh 5 parts
Cycle time	Stopwatch	Average 10 shots
Colour	Spectrophotometer	Three faces against the sample

Gauges are verified every 6 months and callipers every 12, or the figures a case injection molding machine is judged against mean nothing.

3. Dimensions and shot weight: which side of the tolerance

A 520 mm cavity at 0.25 mm gives a window from 519.75 to 520.25 mm. Oversize points to a cavity cut large or hold pressure low, undersize to a cavity cut small or cooling short. Those two faults need opposite corrections, so an out-of-window reading opens an investigation, not a grinder.

Item	Nominal	Tolerance	Check first
Cavity length	520 mm	0.25 mm	Mould temperature, hold profile
Wall	3.2 mm	0.15 mm	Gate size, injection speed
Part weight	2.4 kg	2.5 percent	Melt temperature, back pressure
Base flatness	Zero	0.4 mm	Water circuit, ejector balance

Weight is the earlier alarm because it reads wall and cavity together. A 2.4 kg part at 2.47 kg is 2.9 percent heavy; a calliper still passes the wall, yet the latch no longer closes fully. On a 3.2 mm wall, 1 percent of weight is about 0.03 mm of thickness.

4. Cycle and appearance: pace, weld lines, colour

A case injection molding machine should hold a 58 second cycle as baseline, with 10 consecutive shots inside 3 seconds of it. Widen and the checks run melt temperature, mould temperature, transfer position, then the machine.

Case Injection Molding Machine output: black and grey case side-on, black front, pale grey back, black hinge pin, vertical parting line

Weld lines belong to a deep cavity; depth matters, not presence. A fingernail that slides over one without catching reads about 0.08 mm and can ship; if it catches, raise mould temperature or move the gate. Colour is a difference against the signed sample: within 1.5 is one batch, beyond 3 returns whole, no masterbatch rescues that gap. A lid face sinking more than 0.3 mm means hold time under 8 seconds.

5. Repair, concession or return

A blank disposal clause means every nonconformance is argued from zero.

Defect	Verdict	Disposal	Cost
Flash within 0.15 mm	Reworkable	Trim, re-inspect	3.5 yuan
Cavity out by 0.3 mm	Assembly dependent	Concession, one batch	Zero
Wall 0.2 mm thin	Final	Batch return	28 yuan
Weld line catches	Adjustable	Resubmit after reset	2 hours stopped

Rework covers surface faults only. Flash, burrs and drifted printing can be corrected; a dimensional fault cannot, because correcting it changes assembly, and the cavity on the case injection molding machine has to be recut.

Concessions need batch, quantity and use limits plus a technical signature; a verbal nod is worth nothing in a claim. Ten like defects in 480 pieces, or 2 percent, moves the batch to full inspection, and 3 failures after that return it whole. Repair costs 3.5 yuan against 28 for scrap, and one return burns 6,000 yuan in freight alone.

6. Writing the record so blame can be traced

A record has to reach the mould, the machine and the shift: move a mould to a second case injection molding machine and the cycle shifts 4 seconds while weight moves 0.05 kg, so a sheet without a machine number cannot separate tool from press.

Keep 3 first-offs off the case injection molding machine, one each for supplier, buyer and batch, valid 12 months so a dispute never demands remoulding. Re-verification every 6 months covers cavity dimensions and weight. Response times belong in the record rather than an annex: cause analysis within 24 hours, replacement within 7 days.

Conclusion

An acceptance standard is not a certificate; it is three documents, four measuring habits and three disposal routes bound together. Numbers for the pass line, money and days for the disposal, and the argument has nowhere to live. A missed case always returns as rework, a stopped line or a claim, which is why a case injection molding machine deserves a strict first batch.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.