3-D Printing Creates New Demand and Challenges for Nondestructive Testing
Posted: 2015-8-31
Aerospace manufacturers need to consider ease of inspection when deciding
to use 3D printing, according to a non-destructive testing (NDT) expert who
is developing best practice guidelines for the industry.
Dr Ben Dutton from the Manufacturing Technology Centre in Coventry said
there was a real concern about the lack of inspection standards at a time
when the use of 3D printing, or additive manufacturing (AM) as it is also
known, is on the increase.
"The advantage of AM is that it offers total freedom in designing the part, but
unfortunately that makes it hard to inspect," he said. "The more complex the
component is internally, the more difficult it is for NDT. Another problem is
that the surface finish is typically rougher than conventional manufacturing
processes so inspection methods such as ultrasound, which require a finer
surface finish, are less suitable."
Dr Dutton is leading the drive to develop NDT best practice guidelines on
behalf of ISO through BSI and is involved in a similar initiative with ASTM. He
will be speaking about the topic at a free seminar at the Materials Testing
2015 exhibition in Telford on Tuesday 8 September.
Dr Dutton says trials are being carried out to determine the best way to
examine components produced by AM, focusing on defects that are unique
to AM, and ways to optimise analysis, where a number of NDT methods are
being considered. The guidelines are expected to be published next year.
He says that X-ray computer tomography is emerging as the most promising
inspection technology but it has its limitations and there is room for
improvement to adapt it better to AM and he is aware of research in this
area. While computer radiography is sometimes used, detecting flaws
accurately depends on selecting the correct settings, such as enough
projections to cover the part thoroughly.
He recommends companies use only experienced practitioners, carry out
visual inspection as an initial step, and when in doubt use double testing –
where the product is inspected twice by different inspectors.
"The ideal solution would be to inspect products during the manufacturing
process and take a snapshot of every layer. Some machines already have the
capability to do this, but the next step would be to develop systems which
could spot the defects themselves and raise the alarm," adds Dr Dutton.
"Another solution might be to inspect after machining. The smoother surface
would potentially allow the use of other inspection methods, although this
would add further to the manufacturing cost if the part is found to be
defective after machining. Another post-process is hot isostatic pressing,
which has shown to reduce the size of internal defects in the parts.
"Internationally, a lot of effort is going into creating inspection standards and
some companies are developing their own procedures. There is a real sense
of urgency, particularly in aerospace. For now, manufacturers need to
consider how critical the part is in safety terms and the requirements for
inspection when making the decision to use additive manufacturing."
Dr Dutton’s talk will take place at 4pm on Tuesday 8 September at Materials
Testing 2015 at Telford International Centre. For further information see
www.materialstesting.org
Materials Testing 2015
8-10 September – Telford International Centre, UK
Materials Testing is the world’s most comprehensive NDT exhibition and will
feature over 70 exhibitors, as well as the full-size Bloodhound SSC Show
Car, which aims to set a new world land-speed record. For further
information see www.materialstesting.org, follow @BINDT_MT2015 on Twitter
or call +44 (0)1604 89 3811.
About BINDT
The British Institute of Non-Destructive Testing aims to promote the
advancement of the science and practice of NDT and all other associated
materials testing disciplines - particularly condition monitoring. It caters for
all who work in NDT, from professor to student and from operator to
chartered engineer. For further information see www.bindt.org.
to use 3D printing, according to a non-destructive testing (NDT) expert who
is developing best practice guidelines for the industry.
Dr Ben Dutton from the Manufacturing Technology Centre in Coventry said
there was a real concern about the lack of inspection standards at a time
when the use of 3D printing, or additive manufacturing (AM) as it is also
known, is on the increase.
"The advantage of AM is that it offers total freedom in designing the part, but
unfortunately that makes it hard to inspect," he said. "The more complex the
component is internally, the more difficult it is for NDT. Another problem is
that the surface finish is typically rougher than conventional manufacturing
processes so inspection methods such as ultrasound, which require a finer
surface finish, are less suitable."
Dr Dutton is leading the drive to develop NDT best practice guidelines on
behalf of ISO through BSI and is involved in a similar initiative with ASTM. He
will be speaking about the topic at a free seminar at the Materials Testing
2015 exhibition in Telford on Tuesday 8 September.
Dr Dutton says trials are being carried out to determine the best way to
examine components produced by AM, focusing on defects that are unique
to AM, and ways to optimise analysis, where a number of NDT methods are
being considered. The guidelines are expected to be published next year.
He says that X-ray computer tomography is emerging as the most promising
inspection technology but it has its limitations and there is room for
improvement to adapt it better to AM and he is aware of research in this
area. While computer radiography is sometimes used, detecting flaws
accurately depends on selecting the correct settings, such as enough
projections to cover the part thoroughly.
He recommends companies use only experienced practitioners, carry out
visual inspection as an initial step, and when in doubt use double testing –
where the product is inspected twice by different inspectors.
"The ideal solution would be to inspect products during the manufacturing
process and take a snapshot of every layer. Some machines already have the
capability to do this, but the next step would be to develop systems which
could spot the defects themselves and raise the alarm," adds Dr Dutton.
"Another solution might be to inspect after machining. The smoother surface
would potentially allow the use of other inspection methods, although this
would add further to the manufacturing cost if the part is found to be
defective after machining. Another post-process is hot isostatic pressing,
which has shown to reduce the size of internal defects in the parts.
"Internationally, a lot of effort is going into creating inspection standards and
some companies are developing their own procedures. There is a real sense
of urgency, particularly in aerospace. For now, manufacturers need to
consider how critical the part is in safety terms and the requirements for
inspection when making the decision to use additive manufacturing."
Dr Dutton’s talk will take place at 4pm on Tuesday 8 September at Materials
Testing 2015 at Telford International Centre. For further information see
www.materialstesting.org
Materials Testing 2015
8-10 September – Telford International Centre, UK
Materials Testing is the world’s most comprehensive NDT exhibition and will
feature over 70 exhibitors, as well as the full-size Bloodhound SSC Show
Car, which aims to set a new world land-speed record. For further
information see www.materialstesting.org, follow @BINDT_MT2015 on Twitter
or call +44 (0)1604 89 3811.
About BINDT
The British Institute of Non-Destructive Testing aims to promote the
advancement of the science and practice of NDT and all other associated
materials testing disciplines - particularly condition monitoring. It caters for
all who work in NDT, from professor to student and from operator to
chartered engineer. For further information see www.bindt.org.
