Quality Control Procedures
To produce premium filaments, every production step is of equal importance. In addition to precision equipments, technology know-how and high-standard production workshop, a strict quality control system is required to ensure all finished products had reached its performance standards. The important properties related to filament performance are melt flow index, material dryness, impact strength, and diameter precision. Our lab equipped with melt flow index instrument, dryness tester, impact strength tester, laser diameter tester and hardness tester to check all these properties.
Diameter Tolerance
The diameters of commonly used 3D printing filament are 3mm and 1.75mm and the standard tolerance accuracy requirement is ±0.05mm. Premium filament has the accuracy of ±0.03mm. Lower diameter tolerance means the amount of material extruded through print nozzle is more consistent during the printing process. This consistency directly influences the accuracy and surface smoothness of the printed object.
With our enhanced filament extrusion technology, now we are able to produce 100% of a roll of filament to be within ±0.03mm tolerance range and more than 99.5% of them within ±0.02mm range.
Bump & Bulb Free
A bump is a spot on the filament with the length of 2~5mm and the diameter may exceed 2.0mm. It is one of the reasons that cause the filament blocking in the feeding tube. The causes of the bumps can be either from the gel content in the raw material or mistakes during the filament extrusion process. Gel problems in the raw material are rather complicated that filament manufacturer cannot do anything about it. Therefore, a good source of premium raw materials is very important.
For extrusion mistakes, there are couple of reasons that cause bumps during extrusion.
1. 1. Contamination with different materials. For example, during shifting materials from ABS to PLA, the technician omits the process to clean the screw completely. There are dead spots in the extruder, if the compatibility of these two materials is not so good, the bumps on the filament can be formed. Our standard operation procedure(SOP) is to pull the screw out of the extruder for a complete cleanup and inspection before shifting to other materials.
2. 2. Contamination of other impurities during the pigment mixing or extrusion process. We prevent this possibility by purifying air in the workshop and applying stainless steel filter screen before extrusion head.
3. 3. Improper setup of extrusion temperatures or poor thermal stability that cause crosslinking or overheating of materials and additives. Correct temperature setup and routine facility maintenance are required to prevent these problems.
With the application of premium raw materials and SOPs, we have minimized the possibilities of bumps. However, we found that these precaution steps are not enough and bumps can happen occasionally due to gel issues of raw materials. Therefore, we applied a complete check-up with sophisticate laser diameter instrument during filament coiling to reach the 100% bump-free standard.
Bubbles are majorly caused by humidity inside the raw materials. The procedures of thorough pre-drying of materials and testing dryness by instrument should be implemented.
