One serious weakness of PLA filament is poor heat resistance. Filament companies started to sell heat resistance PLA products charging 30% to 40% higher than normal PLA filaments.
I saw one company’s heat resistance PLA filament. The company recommends performing a hardening process after printing an object with 100% infill: Put the part near boiling water for thirty seconds and remove it.
Serious RepRap users prefer to use ABS over PLA for printed parts if they are used in enclosed 3D Printer. The chamber temperature will rise around 50 to 60 Celsius degrees. I doubt ABS part will maintain rigidity near 100 Celsius degrees.
If PLA filament maintains rigidity around 60 Celsius degrees, I don’t have to buy ABS filament exclusively for 3D Printer parts. I’ve had a can of urethane coat over three years which I hardly use it.
I thought I would apply one layer of urethane coat over a PLA part, then put it in a hot water to test how it increases heat resistance.
On the can it indicates heat resistance: 32 C to 121 C (90 F to 250 F).
I coated a PLA part and let it cured over two days.
I put it in a bowl of hot water for a minute. Over 76 Celsius degrees made it little soft.
Testing at 64 Celsius degrees.
The left side one is a normal PLA part, the right side is urethan coated PLA part that I used previous test. I put two pieces when the temperature was 64 Celsius degrees and kept it for one minute.
I applied force with thumb and index finger against each part. Normal PLA part showed deformation along the pressure point, middle of the vertical section. Urethane coated PLA kept its shape.
I plan to do few more tests about the heat resistance effect of Urethane coat over PLA filament.
Provided recoat interval of the Urethan coat is within 48 hours, I will prepare four samples made out of printed PLA filament: (the recoat interval is 12 hours)
- normal PLA part
- PLA part which has one coat, three days to prepare
- PLA part which has two coats, four days to prepare
- PLA part which has three coats, five days to prepare