The need for qualification of 3D printed parts

Point of view | 14 December 2020

By Aditya Gupta and Anas Rais

One of the greatest challenges in the 3D printing world is getting parts qualified. Since less than 1% of companies are invested in 3D printing, the qualification of parts has been a challenge.  

Once a part is 3D printed, it is not always ready to use. Most of the time, parts must be certified for specific use cases. 

Certification of individual 3D printed parts require long, complex, and expensive operations. It would be more realistic to certify the whole manufacturing process, further leading to certification of the parts produced within the process. 

Companies producing everyday goods must certify their manufacturing processes. It is a must to guarantee that the end products produced also have the desired physical properties (toughness, resistance, etc.). 

The more salient the part is, the more important its certification will be. Hence, aerospace, automotive, and medical industries are in alarming need of certified AM processes. 

Indeed, certifying a manufacturing process eliminates the need to physically test and validate every single part but for small scale production certifying the process may become costly and validating each produced part makes more sense. 

Therefore, to become truly industrial and scalable fabrication techniques, AM processes need to be certified. To obtain a certified AM process and guarantee quality across time, it is necessary to combine numerous guidelines. 

How Spare Parts 3D qualify parts

Our widespread network, spread in more than 20 countries, can deliver metal and plastic parts across Europe, Middle-East, Asia and America. 

We apply systematic standard requirements and associated test procedures for 3D printing processes. This way we can hedge risks and ensure the same levels of fidelity that are seen in conventional processes (casting, forging, machining). 

We follow industry codes and standards such as ASME, ASTM, ISO or as per your requirements, whichever is more stringent, to comply with the industry requirements.

We are resilient and adapt to alterations as per the requirement of the client or the necessity of the process. The qualification is heavily based on the number of parts to be produced.

Validating unique and very small series production

Often we deal with companies that may want to test the efficiency of the process with small scale production or have very small inventory needs especially in case of unique parts. In that case, we test each part.

We provide an inspection certificate according to EN 10204:2004 that specify the legal and regulatory requirement that must be provided to those purchasing products as proof of quality and product specification.

We carry out material testing at service temperature to validate the required material properties such as tensile strength, impact, corrosion, etc.

Also, NDT inspection such as CT scan, ultrasonic, dye penetration, hardness tests is done for each part.

In addition to those, we provide ad-hoc tests & inspections to comply with more specific requirements (ISO balancing for rotating equipment, ASME welding inspection, etc.).

Validating small series production

With small series where part number ranges between 20 and 100, we use standards applied across part categories. 

We work on different failure modes that could exist using a particular process and the part type and work on minimizing them. 

For instance, while working for a large transport company, we created a design validation checklist that enlists all the requirements to be met by the product design for the project to be successful under several attributes such as weight, deflection, safety factor, total stress, etc. 

We recreated the design that meets all the design requirements. This way we were not only able to produce parts with high accuracy but also optimised it for better performance.

Validating large scale production

With large scale production categorising different parts into part categories become difficult and time-consuming. Hence, we work by developing a control plan for our suppliers and use a suite of statistical process control (SPC) techniques to assess the repeatability of the processes and identify defect patterns. The proposed approaches aim at extracting the relevant information content from image data, by describing the spatial or Spatio-temporal patterns to determine both when and where a defect has originated. 

This technique helps us find out the root cause and work to minimize the failures. 

While working over 40k parts for a large semiconductor producer client, we came up with Failure Mode and Effects Analysis(FMEA) on the relevant process to identify all its failure modes and their potential root causes to establish a relevant control plan for our suppliers.

One particular issue we faced was related to dimensional accuracy, the process needs to show repeatability over a range of parts. To tackle this issue, we performed SPC and correlation analysis on several batches to identify the root cause of the problem. Upon these studies, adjustments in processing temperatures were done to optimize the parts’ shrinkage tendency during cooling. This resulted in the improvement of the machine’s dimensional repeatability.