Medical
implants need to be made from high quality orthopedic components so that they
can be used and kept by patients for as long as possible. This reduces or even
eliminates the need for additional surgical and non-surgical procedures down
the road. A good way to ensure the level of quality required is for orthopedic
device manufacturers to measure with high-precision air gages during the
product’s development and production phases.
Orthopedic
Device Manufacturing Challenges
Machining
and cutting are some of the individual manufacturing steps that must be consistently
stable in order to achieve precise orthopedic components that meet the necessary
high-quality standards. Oftentimes, as parts move through the manufacturing
process from raw materials to final products; geometric characteristics, surface
finish, and dimensional tolerance become increasingly critical.
Tight
tolerance is a dimensional characteristic that is often measured at the end of
the orthopedic device manufacturing process. It focuses on the tolerance on the
tapers that are used to match the components together. For example, most knee
and hip implants utilize tapers to enable optimal alignment and to secure (or
lock) the parts into position. During these processes, the control of both size
and taper will determine the performance of the orthopedic implants over their
service lifespan.
Air
Gaging: The Preferred Method
From
having the proper resolution to measure tolerances to having the right design
characteristics to fix parts together, today’s gages have to be robust when it
comes to manufacturing orthopedic implants. For many manufacturers, air gages
have become the inspection tool of choice for controlling such critical
parameters. Air gaging has proven itself to be an extremely precise measurement
method that provides very high resolution. It is now often used in applications
(e.g., precision medical tapers) where the tolerance tightness is less than
±0.001 in.
That’s not all as air gages are particularly well suited for checking dimensional relationships. They are easy to use, produce results quickly, and can last for years, even under the toughest shop conditions. One of the reasons why air gages are so useful for measuring orthopedic tapers is that they feature air jets, which are small orifices that emit air, and can be used to measure parts at the point of manufacture.
Common
Air Taper Gage Variations
Below
is a quick look at the different types of air taper gages that are used in
modern applications:
- Jam-fit style air tool: Considered the most common type of air gage taper tooling. It
features two pairs of jets and is designed to create a jam fit between the tool
and the part (on opposing air circuits). This tooling does not measure part
diameters but showcases the two points’ diametrical differences on a particular
workpiece. - Clearance style air tool: Also known as a shoulder style air
tool, this gage is used when an air taper ring
cavity needs to be sized to accept the entire taper part. In addition, the air
gage can be used to inspect for barrel and bell-mouth shapes, as well as
measure diameters at known heights. - Simultaneous fit air tool: The third gage is a cross between the previous gages; it is essentially
a jam-fit air gage that takes references from the face of the datum surface
with the aid of an indicator. It is often used to indicate how far an air tool
goes into the part that’s being measured.
