MDTmag.com 12 / March 2014
By Mark Fridman, Sales & Marketing Manager,
Mark- 10 Corp.
The decision to purchase a piece of measuring equipment should never be taken lightly. Whether procuring
a drop indicator or a multi-million dollar
measuring system requiring multiple levels
of approval, the result of a quality control
measurement can only be as good as the
equipment used to perform it. Reflexively
seeking the lowest price or a familiar model
number should be resisted until a thorough
Force measuring instruments have come a long way. Today’s equipment
opens up possibilities once in the exclusive domain of more complex
systems. As illustrated in this article, force measurement instruments are
able to address the testing needs of medical device manufacturers for a
variety of applications.
assessment of the quality testing challenge
and available solutions has taken place. This
couldn’t be truer when purchasing equipment
to measure the amount of force required to
break, tear, actuate, or otherwise achieve a
quality control objective with regard to the
mechanical properties of a material or a part.
Why Rethink Force Measurement?
Force measurement refers to the measurement of a compressive or tensile force.
Closely related – but not to be confused with
weighing and materials testing – the medical
device manufacturing industry is rife with
applications for force measurement. Typical
examples include determining packaging seal
strength, tube termination pull-off testing,
blade sharpness testing, spring testing,
fastener torque testing, syringe plunger force
testing, and many others.
The most familiar embodiment of force
measurement – the ubiquitous force gauge
– had its origins many decades ago. Having
evolved from a simple spring weighing scale,
the handheld force gauge of today can be
as accurate and advanced as a closet-sized
tensile testing machine from years ago.
Force gauges today are joined by test
stands that have also grown in sophistication.
Usually, a screw-driven crosshead moves a
force gauge up and down to produce a force,
and reverses when the test is complete. A
test stand’s controller can regulate the rate
of speed; stop the motor when a specified
load, distance, or sample break has occurred;
cycle the crosshead; and accept commands
from a PC. Much like innovation in personal
computing has progressed rapidly, so too has
the ability of force measurement systems to
provide useful and cost-effective answers to
quality control questions. These answers have
upended previously held notions about what
a tension or compression testing apparatus
must look like.
Determining whether force measurement
equipment can help the Quality Control
engineer or researcher satisfy an ISO,
ASTM, or internally developed standard
starts with a thorough inspection of the re-
quirements of the standard. Consider some
of the core parameters typical of a standard
• Accuracy and resolution of the measuring
• Unit of measurement
• Proper sample preparation and dimensions
• Linear speed of the testing apparatus
• Nature of the sample gripper or fixture
• Requirement for force measurement only
or force vs. displacement
• Interpretation and storage of results
When comparing these parameters to the
capabilities of a force measuring instrument,
it may become evident in many applications
that a system consisting of a test stand, force
gauge, suitable grips, and data collection
software can satisfy the application.
A motorized test stand can be programmed to run at a specified rate of speed
and can be fitted with an internal scale for
displacement measurement. The force gauge
can display peak and real time values with
an internationally accepted level of accuracy,
and numerous standard grips and fixtures are
readily available. In many cases, custom fixtures are fabricated to reflect the great variety
of sample shapes and sizes.
Data collection software captures peak
The compression force of a syringe plunger can be
determined through force measurement equipment.