Surface World December 2019 Surface World December 2019 | Page 40

MASKING – TAPES, CAPS & PLUGS
Masking weld nuts
Weld nuts require additional
care when painting and
there are products available
to help you quickly and
accurately mask weld nuts.
Weld nuts are common in many industries
and are used where the main body of a part
doesn’t have the thickness to support a
threaded bolt. They are often used on frames
and fabrications that need painting or
surface finishing for corrosion resistance.
As weld nuts are used where the assembly
of parts is required, it is important that the
threaded portion of the weld nut does not get
coated with the rest of the part. There are
numerous plugs available to mask threaded
holes, but now there is a range of masking
plugs available specifically designed for
masking weld nuts.
The weld nut plug (WNP) is inserted into the
weld nut and pulled through from the back
of the nut. A thin flange on the front of the
plug collapses as the plug is pulled through
the nut. This flange then springs back once it
is through the threaded portion of the nut.
There is a further thicker flanged area on the
plug, which acts as a stop to ensure the plug
cannot be pulled through the nut.
This stop and collapsing flange arrangement
ensures the plug is in the correct position for
the finishing process.
The weld nut plug features a chamfered end, to
show which end of the plug should be inserted
first. This chamfered end also makes it easier to
install the plug. The other end of the plug is a
T-shape, which speeds up the removal of the
masks after the finishing process.
For weld nuts that do not have a through
hole behind them, there is the blind weld nut
plug (BWNP). This plug pushes into the weld
nut and masks the threaded portion of the
weld nut. There is a thin flange on the front
of the plug that collapses as the plug is
inserted and springs back once the flange is
through the
threaded portion
of the nut. This
flange then
helps retain the
plug in the nut
through the
finishing
process.
the size of the weld nut they fit.
If you need to mask weld nuts, a good
masking supplier such as Caplugs or any of
their distribution partners such as Greentree
can provide samples of these weld nut
masks for you to evaluate.
John D. Gill
John D. Gill is an Engineer with
experience in masking and product
protection throughout the UK,
Europe and USA. He can be reached
at www.johndgill.com and via
Twitter @masking101
Weld nut plugs pull
through weld nuts
and mask the
threaded portion of
the weld nut.
Both of these
styles of plugs
come in a range
of sizes to suit
metric weld nuts.
The different
sizes are colour
coded to identify
Blind weld nut plugs
are ideal to mask
weld nuts where
there is no hole
behind the weld nut.
38
DECEMBER 2019
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