Problem & Solution

Practical answers to common plastic material challenges

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Q

PC Warpage Deformation

A

For PC warpage, mainly check 'holding pressure and uneven cooling' rather than crystallization: as an amorphous material, PC's warpage is more of a stress problem; restraining the holding pressure and making the temperature field uniform, warpage is mostly controllable.

Molds & Tooling PC; warpage; uneven cooling; holding pressure; stress

Q

PC Flash

A

With PC's high-pressure process, the clamping margin must be left sufficient.

Injection Molding PC; flash; clamping force; holding pressure; parting line

Q

PC Jetting Marks

A

Let the melt stream 'stick to the wall first and then spread out', and the jetting marks disappear.

Injection Molding PC; jetting mark; snake pattern; gate; injection speed

Q

PC Weak Weld Line Strength

A

PC weld lines rely on 'high-temperature meeting + good venting': PC molecular chains have large rigidity, and the meeting temperature is decisive; plan the gate in advance for structural parts to move the weld line out of the load path, rather than reinforcing afterwards.

Molds & Tooling PC; weld line; venting; melt temperature; strength

Q

PC Gate Blush (Gate Mark)

A

PC gate blush is solved by 'enter slowly, flow fast': lower the speed through the gate, enlarge the gate, and then stabilize the holding pressure switchover; the gate area of transparent parts is where shear is most concentrated and needs key care.

Molds & Tooling PC; gate blush; shear; injection speed; mold temperature

Q

PC Short Shot Caused by High Viscosity

A

For PC short shot, first 'raise temperature and speed up', then 'large gate', and finally 'change grade': high viscosity is PC's nature; when the structure allows, shortening the flow length and enlarging the gate is more effective than forcibly raising pressure, and also better protects the mold.

Injection Molding PC; short shot; high viscosity; melt temperature; injection pressure

Q

PC Product Stress Cracking

A

The core of PC management is 'internal stress management': cracking is often a time bomb that explodes after leaving the factory; restraining the holding pressure and eliminating uneven cooling is far more effective than screening cracked parts afterwards.

Molds & Tooling PC; stress cracking; residual stress; annealing; solvent

Q

PC Product Yellowing

A

PC yellowing = 'thermal history exceeding the standard': lower temperature, shorten time, and reduce shear all together; the actual melt temperature is often higher than the set value, shear heat must be actually measured; PC has strong thermal sensitivity, and temperature management must leave s...

Molds & Tooling PC; yellowing; thermal degradation; residence time; shear heat

Q

PC Internal Bubbles

A

PC bubbles are investigated by the three-way method of 'water, vacuum, entrained air': first verify drying, then look at holding pressure, and finally check venting; transparent parts have zero tolerance for bubbles, and drying verification is the first and most important checkpoint.

Production & Quality PC; bubble; vacuum bubble; holding pressure; drying

Q

PC Brittleness Caused by Hydrolytic Degradation

A

PC hydrolysis is an irreversible 'invisible killer': products with normal appearance may already be performance-scrapped; drying for PC is not a suggestion but a hard threshold, moisture content verification must be incorporated into the startup SOP, otherwise it is handing unqualified products d...

Material Drying PC; hydrolysis; brittleness; molecular weight; drying

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