ADDITIVE MANUFACTURING
A design-driven process
In traditional manufacturing , many costs are hidden in the supply chain . Additive manufacturing will have significant impact on the design and size of this system , reducing its associated costs . Industry experts forecast that additive manufacturing market value will reach U $ 50 billion between 2029 and 2031 while reaching US $ 100 billion between 2031 and 2044 . This explosive growth will undoubtedly disrupt how users think , plan and execute existing manufacturing process .
Potential alternative processes may include :
■ Additive manufacturing processes , including additive layer , powder jetting , selective melting and wire-fed variants .
■ Enhanced rolling , drawing and forging processes , including rotary forging , flexible forming , flow forming , cladding and vacuum forging .
■ Promotion of wrought properties in Near Net Shape manufacturing .
■ Hybrid forming processes .
The strengths of additive manufacturing lie in those areas where conventional manufacturing reaches its limitations . The technology is of interest where a new approach to design and manufacturing is required to come up with solutions . It enables a design-driven manufacturing process - where design determines production and not the other way around .
Additive manufacturing allows for highly complex structures which can still be extremely light and stable . It provides a high degree of design freedom , the optimisation and integration of functional features , the manufacture of small batch sizes at reasonable unit costs and a high degree of product customisation , even in serial production .
Metrology for AMmanufactured parts
“ Undoubtedly there are many benefits associated with the use of additive manufacturing ( AM ) as a production technology . Across industries , manufacturers exploit the fact that through the use of AM they can not only build complex parts — in one piece — which were previously impossible , but they can also build stronger , lighter weight parts , reduce material consumption and benefit from assembly component consolidation across a range of applications ,” commented Eric Felkel , Product Manager ( Optical Profilers ), Zygo Corporation .
“ These advantages have been well documented during the last 10-20 years as AM has emerged as a truly disruptive technology for not just prototyping , but also production , and are invariably seen as being enabled by the additive hardware that builds the parts .”
Zygo is working with Richard Leach , Professor in Metrology at the University of Nottingham , Nottingham , U . K ., on various projects relating to the use of metrology in AM . It is Leach ’ s view that the issue of metrology is crucial to the success of AM as it begins to establish itself as a true production technology .
“ Our focus today is on producing a Good Practice Guide along with ASTAM , showing OEMs which metrology solutions are in place today , and how to get the best results from
Zygo metrology for AM .
these when applied to AM surfaces , and setting the instrument up in the best way to understand the data ,” said Leach . He works with a number of metrology instrument suppliers , using a variety of measurement technologies .
“ Imagine you are making a turbine blade in an AM layering process , and you see that there was a blip in the topography in layer 4 . This layer will in-time be covered up , so its characteristics will be fundamentally different by the time the finished part is complete , and it is at this moment impossible to know — without the clarity that good metrology provides — whether the blip is in fact still there when the build is complete , and if so , if it was actually significant in the first place …. Essentially , we are working on — but still haven ’ t completely solved — the problem of understanding which issues you get on the surface and under the surface when
Metrology for AM-manufactured parts ( Zygo .).
using AM , and how these relate to product functionality . Therefore , it is difficult to predict the mechanical properties , the thermal processes , the fatigue properties etc … from the types of structures we are seeing postprocess . Defect-function analysis may allow us to move towards controlled AM by just stopping the process when things go wrong , as right now , we spend hours building a part that may , in fact , have a problem in layer one ,” he continued . Despite these challenges , many companies are already using advanced AM successfully for the production of critical parts and components , often in aerospace applications where part failure is not an option . To ensure that these AM-produced parts conform fully with design intent , part suppliers undertake far more mechanical testing and metrology verification than they would normally employ for conventional manufacturing processes .
Necessarily , manufacturers are forced to focus on process development and throw all the validation resources they can to “ prove ” the integrity of the finished AM part . This latter is effectively a belt and braces approach , relying on Gage R & R reproducibility and repeatability as a stand-in for a more rigorous measurement uncertainty approach when evaluating the integrity and functional characteristics of AM parts . The current solution is what could be termed “ extremetesting ”.
“ Everyone blames the confusion on a lack of standards for measuring AM parts , but this is not where attention should be focused ,” said Leach . “ You cannot develop standards if you don ’ t have the correct measurement technology in place to start with . Standards being developed without the technology solution ready to use are actually worse than no standards at all . That is why the emphasis with Zygo and other metrology instrument suppliers is on adapting metrology solutions to make them better aligned with the unique characteristics of the AM process and AM end-use parts .” n
38 | sheetmetalplus . com | ISMR April 2021