SUMMER 2016

130
THE DISTRIBUTOR’S LINK
ANTHONY Di MAIO MOST FEQUENTLY ASKED BLIND RIVET QUESTIONS from page 52
How do you read the grip range of hard metric Closed-end blind rivets are referred to as seal
and inch blind rivets?
rivets. I know they are sealed through the center
Hard metric refers to exact metric blind rivets such because it is a closed-end but what seals it on
as 3mm, 4mm, 5mm, & 6mm diameter, not the soft the blind barrel outside diameter?
metric conversion such as 3.2mm, 4.8mm, 6.3mm The closed-end blind rivet prevents liquid or gases
diameters that are direct conversion of the inch to metric from passing through its center because it has a closedend
barrel. The sealing ability of the outside diameter of
blind rivets.
Inch size blind rivets have the maximum grip range the set closed-end is questionable because the condition
in their part number. Example:- size 44 inch blind rivet, of the hole in the work piece to be riveted plays a large
the first 4 has a base factor of 1/32 of an inch.
part on how well it will seal on the outside diameter.
Therefore, 1/32 x 4 = 1/8, which is the diameter There could be burrs on the hole of the upset side of the
of the 44 blind rivet. The second 4 has a base factor of closed-end rivet that can prevent the rivet-upset side to
1/16 of an inch, therefore 1/16 x 4 = 1/4 which is the not set properly on the work piece.
maximum grip range of a 44 inch blind rivet. The first To ensure that a closed-end blind rivet is completely
number in an inch part rivet part number is the diameter sealed around it’s outside diameter against liquid, gas,
of the blind rivet and the second number or numbers is air etc. is to apply a sealant to the barrel side of the
the maximum grip range of the blind rivet.
flange. There are companies that will apply the sealant
Example:- size 410, we know the 4 = 1/8 diameter, to a closed-end blind rivet and the sealant has a long
10 x 1/16 = 5/8 which is the maximum grip range of a shelf life. We can tell you the best sealant to use for your
410 blind rivet.
application and which company can process the closedend
rivets for you. Sealant is also being applied to all
Hard metrics is a complete different situation.
Example:- 4 mm x 8mm hard metric blind rivet, 4 mm is types of rivets and rivet nuts.
the diameter of the blind rivet and the 8mm is the length
of the barrel of the blind rivet. The 8mm dimension has What visible characteristics can I look at that
no relationship to the maximum grip range of the blind will tell me if the blind rivet has been produced
rivet. You must refer to the manufacturers catalog to find with quality in mind?
out what the minimum and maximum grip ranges are for Look at straightness of the mandrel. If the mandrel
the 4mm x 8mm blind rivet.
has a slight bent, that mandrel has not been produced
properly. The straightness of a mandrel should be within
What are large flange blind rivets used for? .008 T.I.R. (Total Indicator Reading) for the length of
Large flange blind rivets were designed primarily the mandrel. A mandrel must be produced from straight
to distribute the setting force over a larger area when wire. The mandrel-making machine has straightening
setting a blind rivet. Example:- If you are riveting a fairly rollers that will straighten the wire and produce a straight
soft plastic work piece to a metal; work piece and the mandrel. A blind rivet with a slightly bent mandrel, can
fairly soft plastic is on the flange side of the blind rivet affect the ejection of the spent mandrel when the blind
and you use a dome head (standard head) blind rivet, rivet is set.
you would depress the dome head in to the plastic. If View the point of the mandrel to see if there are
you use a large flange blind rivet, you would only slightly burrs or wings attached to the mandrel point. If yes, this
depress into the plastic because the setting force is mandrel was made with dull cutters and was not properly
being applied to a large area.
de-burred in the de-burring machines. Is the rivet body
The setting force of the blind rivet is generated free of burrs? There should be no burrs anywhere on the
when the blind rivet setting tool is pulling the mandrel rivet body.
to its ultimate tensile strength and breaks. The mandrel Check to see if the flange diameter is concentric with
tensile strength is the same for all blind rivet body’s the rivet body barrel. The flange and rivet body should be
head configurations of the same alloy blind rivet.
concentric with each other within .008 T.I.R.
ANTHONY Di MAIO