Can case raw material preparation shorten drying with more heat?

Answer: No. Above 90 °C for PP or 85 °C for ABS the pellet surface softens and bridges, sealing water inside. Add a desiccant dryer instead.

Can the masterbatch ratio be set by eye?

Answer: No. A ΔE near 1.0 is invisible on the floor. Lock the unit between 2 and 4 percent and verify each lot.

Is 20 percent regrind always safe?

Answer: Only by location. Panels tolerate 20, hinge and handle roots stay at 10, clear parts take none. Re-run drop and thickness after setting it.

Why hold back the first shots after a color change?

Answer: Residual pigment needs about 20 shots to clear. Held aside, they get a second look instead of downgrading a batch.

What records does case raw material preparation need?

Answer: Four: grade and lot, drying start, end and temperature, masterbatch and regrind percentages, first-article thickness and weight. With all four, a suspect lot is pinned within two hours.

Case Raw Material Preparation: Drying, Color, Regrind Ratios

Quick answer: Case raw material preparation turns purchased pellets into a blend that goes straight into the hopper: dry to a moisture ceiling, dose masterbatch to a color tolerance, blend regrind to a scrap ceiling. Run the three out of order and the case shows it in wall thickness, color or impact strength.

What Case Raw Material Preparation Covers
Drying: Temperature, Time and Moisture Ceiling
Color: Masterbatch Ratio and Color Changes
Regrind: Setting the Scrap Ratio Ceiling
Mixing and First-Article Confirmation
FAQ

1. What Case Raw Material Preparation Covers

A case body is PP copolymer or ABS, and a 250-tonne press eats 300 to 500 kg a shift, 12 to 20 sacks of 25 kg. Case raw material preparation runs from the warehouse rack to the drum tipped into the hopper, judged on four numbers: moisture, color difference, regrind share and particle size spread.

The four gates run in a fixed order: incoming inspection for grade, lot and melt index; drying under the moisture ceiling; coloring over dry pellets; regrind last, because scrap needs its own drying pass. Plants that color first find masterbatch caked in the hopper.

Check	Method	Accept limit
Grade and lot	Delivery note against bag code	All three match, else reject
Melt index	Spot test	Within 10% of nominal
Moisture	Meter, three points	Per grade ceiling

2. Drying: Temperature, Time and Moisture Ceiling

For PP, drying in case raw material preparation runs 80 to 90 °C for two hours. ABS is polar: 80 °C for three to four hours, down to 0.10 percent. A case with a PC window needs 120 °C for four hours and 0.02 percent. Over-drying fails too: PP above 90 °C for four hours goes tacky and bridges.

Dryer type matters more than setpoint: hot-air hoppers draw shop air, so at 80 percent humidity four hours changes nothing. A desiccant unit at minus 20 °C dew point gets there in two hours. Log temperature and level every two hours.

Material	Temp	Time	Moisture
PP copolymer	80–90 °C	2 h	0.05%
ABS	80 °C	3–4 h	0.10%
PC	120 °C	4 h	0.02%

3. Color: Masterbatch Ratio and Color Changes

Dosage runs 2 to 4 percent: pale and beige at 2, charcoal and olive at 3 to 4. Under 1.5 percent the pigment cannot disperse and the surface clouds; above 5 percent the carrier mismatches and impact strength falls.

Carrier family has to match, PE for PP and ABS or SAN for ABS. Meter on a loss-in-weight unit at plus or minus 0.5 percent; hand blending needs 20 rpm for five minutes. Read color under D65: 0.6 within a lot, 1.0 lot to lot. Pale to dark purges with 3 to 5 kg, dark to pale with 8 to 10 kg and a pulled nozzle, and the first 20 shots stay quarantined.

4. Regrind: Setting the Scrap Ratio Ceiling

In case raw material preparation, grind to 6 to 8 mm, within 2 mm of virgin pellet size; a wider spread separates the fractions and wall thickness oscillates. Check screens weekly, since a torn one passes 20 mm chunks.

PP bodies run to 20 percent, ABS to 15, while hinge bosses, latch seats and handle roots stay at 10. Each extra 10 points costs 5 to 8 percent of Izod impact, and the higher melt index hides a thin wall.

Location	PP ceiling	ABS ceiling	Note
Lid and base panels	20%	15%	Re-test drop
Hinge and latch seats	10%	10%	Load path
Handle and trolley	10%	5%	Fatigue
Clear window	0	0	No regrind

5. Mixing and First-Article Confirmation

Blend for 3 to 5 minutes at moderate speed; friction adds 5 to 8 °C and makes PP tacky. Keep a batch to one shift, about 300 kg; material blended today and molded tomorrow reabsorbs moisture.

The first article checks eight wall-thickness points, weight within 1.5 percent, and color against the plaque under D65. If it fails, check the order of the three jobs before touching process settings.

Conclusion

Case raw material preparation is three jobs behind two gates: drying sets moisture, coloring sets ΔE, regrind share sets impact. One batch card carries all of it, and a number that does not reconcile there cannot be fixed at the press. Fix the order, keep the records, sign the first article, and case raw material preparation is genuinely complete.

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.