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Highlights of the Engine Valve
Remanufacturing Process
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You can simply drop your
engine valves into the shipping crates that we provide as the engine valves are being removed from the
heads in your plant. Since we (like you) are starting with a core product, we must
pre-clean and sort every part when it arrives.
When you place an order, one of our Initial
Inspectors will retrieve the necessary number of engine valves and 100% visually inspect them for
defects such as worn or damaged keeper grooves, bends, obvious cracks in the faces or
stems, etc. Any part found to have a defect is scrapped immediately.
The tip of each engine valve is then ground to
remove any "cupping" as a result of wear and to reestablish perpendicularity
with the valve stem. If you require, each of the engine valves in your order will be ground to
the "same length".
Engine valves requiring hard chrome plating are
prepped and directed to our own electroplating facility. Most engine valve manufacturers that
boast of chrome plated valve stems apply only a "flash" chrome layer. In our opinion,
this is done more for looks when the engine valve is pulled from the box rather than for
performance once its in the engine. At our plating facility, we apply at least 0.003 in.
(diametrically) of hard chrome to our standard sized engine valves, 0.008 in. to our +8 oversized
engine valves, and 0.015 in. to our +15 oversized engine valves. Of course, we can control the chrome
thickness and finished diameter to meet your specific requirements. We also carefully
control the chrome location to ensure that (1) chrome does not interfere with the keepers
and (2) the entire valve stem within the guide is plated.
 The electroplating process generates hydrogen gas. While engineering controls
are made to minimize the amount of hydrogen gas, hydrogen entrapment within the chrome
plating is inherent to all hard chrome electroplating operations. If not removed, the
hydrogen will cause the part to blister or crack. Therefore, each plated
engine valve is baked
for four hours at a constant temperature to release the hydrogen gas. The baking process
is known as hydrogen embrittlement relief.
To ensure that our electroplating process
was completed properly, we subject all plated parts to chrome adhesion verification tests.
This process identifies any part that may not have been properly prepped, may have become
contaminated, or otherwise had its plating process interrupted.
We verify the tip hardness on all exhaust valves, any
engine valve known to historically have a problem with tip hardness, and any other valves you
specify. All engine valves that do not meet your minimum requirement are scrapped.
Each engine valve stem is finish ground to your exact
specifications. Through regular sampling of parts during the process, we closely monitor
and record the engine valve stem diameter, stem finish and stem lobing to ensure that we not only meet,
but exceed your expectations. We typically maintain a manufacturing tolerance of plus or
minus 0.00035 in. on stem diameter with process capabilities of 2.0 Cpk and better. Laser
micrometers are used to verify stem diameters out to 1/100,000 inch.
Engine valve faces are ground with respect to the
stems to ensure proper seating in your heads. Our resulting runout is less than half of
the OEM mean. We also maintain a surface finish of no more than 32 µin. Ra, (typically 12
µin. Ra) and hold face angles to +/- 15 minutes. Once again, these specifications can be
adjusted to meet your needs. We also offer eddy current crack detection on all faces to
eliminate any valves with subsurface microfractures.
During packaging, samples from each order
are pulled for final inspection and subjected to at least 5 different tests.
Summary:
During each step of the remanufacturing
process, your parts are being
continually inspected,
measured, gauged and otherwise qualified using the best possible gauging and measuring
equipment. We utilize everything from digital and laser micrometers, to optical
comparators, digital profilometers and digital hardness testers.
The next time you go to order new
engine valves
from an OEM, ask them for the specifics on their manufacturing processes and the
tolerances that they maintain. Then ask them to provide you with something outside the
norm for the same price.
If our remanufacturing process has yet to
convince you that you are buying a high quality product, do not hesitate to
contact us with your questions or concerns. If you're
still not convinced that CalValvesTM are worth a try, maybe this will
per$uade you.
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