Self Clinching Flush Head Studs for Stainless Steel Installation and Performance

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NORTHERN PRECISION LTD

Specialist Fasteners for Sheet Metal

+44 (0) 1302 836010

+44 (0) 1302 831555

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sales@npfasteners.com

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SELF-CLINCHING

Clinch Nuts Flush Nuts Blind Nuts Miniature Nuts Nyloc Nuts Locking Nuts Floating Nuts Flush Head Studs Flush Head Studs for Stainless Steel Reduced Flush Head Studs Thin Panel Non-Flush Studs High Strength Studs Thin Panel High Strength Studs Flush Head Pins Flush Head Tapered Pins Concealed Head Studs Through & Blind Standoffs Grounding Standoffs Thin Panel Standoffs Quick Release Standoffs Keylock Standoffs Concealed Head Standoffs Flush Panel Screw Assembly Panel Fasteners Phillips Head Panel Fasteners Low-Profile Panel Fasteners Plunger Assembly Self-Clinching fastener Do’s and Don’ts Self-Clinching fastener problem solving guides Self-Clinch in harder panels

Testing Method

Hardened bush. A minimum of 6 fully engaged threads is recommended on both sides.

Test panel held firmly in vice.

Applied torque from dial measuring torque wrench.

Minimum grade 5 bolt (grade 8 for NHTS & NHFE fasteners).

Torque-out testing of Self-Clinching Flush Head Studs should be performed by the gradual application of torque as shown while the test panel is securely held in a vice. The bolt must be of a sufficient grade to resist thread stripping. Torque must be gradually applied until failure is observed and a maximum applied torque reading is recorded. Failure mode is the stud turning in the panel, cam-out, or dependent on stud type/size, thread failure.

Pull-through test for Self-Clinching Flush Head Studs should be performed by the gradual application of an axial load as shown. A hardened bushing with a through-hole 0.5mm greater than the diameter of the thread should be centred over the stud and inserted into the test rig lower link. A hardened threaded bushing should be inserted into the test rig upper link and screwed down onto the stud. An axial load is then gradually applied on a tensile testing machine to separate the links until a failure point is reached. Please note that the pull-through values obtained during this test do not indicate the axial strength of the stud threads. Pull-through values pertain only to the amount of force required to pull the stud through the panel.

Tensile testing rig upper link

Tensile testing rig lower link

Hardened bushing

Hardened threaded bushing. A minimum of 6 fully engaged threads is recommended.

Applied Load.

Do not remove any extra material or chamfer the hole as this could result in improper installation or reduced performance.

HRB (ROCKWELL HARDNESS B SCALE) Ensure that you are installing into a panel that is ductile and at or below the published maximum recommended hardness for the fastener.

Ensure that attention is paid to the minimum hole centreline to edge dimension for each fastener. Installing too close to an edge or bend could result in improper installation or reduced performance. Minimum centreline to edge dimensions shown for each fastener apply to one edge only. If this distance is applied on multiple sides there will be significant panel distortion unless the panel edges are supported during installation.

Performance

Thread size

Max. nut tightening Torque (Nm)

0.90

Installation (kN)

Torque-out (Nm)

Pushout (N)

Pull-thru (N)

2250

3200

3350

4250

1.8

6.5

11.0

16.0

3500

8000

10000

15000

Test Sheet Material

1.5mm Stainless

1.8mm Stainless

All performance figures are averages obtained over a range of installations and should be used as an indicator only. Panel material, hole preparation, installation tooling and method can affect part performance. We always recommend that you carry out your own tests in the actual application. Please call our sales team and we will be happy to provide you with samples as well as offering technical assistance.

2.10

4.30

7.20

Panel Hardness

Ensuring that the panel is within the recommended thickness range (1.0 - 2.4mm for M3, M4, M5 and 1.6 - 3.0mm for M6 parts), punch or drill the correct size hole. Do not deburr or chamfer the hole prior to installation as this will remove material required during the clinching process. It is preferable to install the fastener from the punch side of the panel. Place the fastener in the prepared hole in the panel and then locate the fastener in the anvil. With the panel held level, apply a parallel squeezing force until the head is installed flush to the panel surface. Do not over squeeze the fastener into the panel as this will result in panel deformation. When installing Self-Clinching fasteners, please pay attention to the minimum hole centreline to edge and parent material hardness limitations.

Anvil Dimensions

B +0.10

4.90

3.76

6.10

7.82

A +0.08

4.04

3.05

5.08

6.05

Thread size

S ±0.025

0.25

0.51

C +0.10

5.77

4.52

7.11

8.74

R1 Max.

0.08

R2 Max.

0.13

Length of stud +3.2mm min.

95°

45°

Flush Head Studs for Stainless Steel require a special staking- ring anvil for correct installation. The staking-ring aids displacement of panel material to ensure that the annular clinch feature is fully filled. For longevity, it is recommended that anvils should be a minimum of 55HRC.

Material & Finish

400 Series Stainless Steel (A2) parts are suitable for installation in ductile panels with a maximum recommended hardness of 92 HRB.

Part Number Examples

Part number is made up as follows: (Type)-(Thread)-(Length)-(Material/Finish code) For example: NFH-M4-12-400 (Flush Head Stud-M4-12mm long-400 stainless steel) Use part designation NFHD to specify a dog-point thread lead-in (special order).

Info

Self-Clinching Flush Head Studs for Stainless Steel provide strong reusable captivated male threads in thin stainless steel panels. Utilising a special proven castellated clinch feature, this fastener has excellent torque-out, pull-through and push- out characteristics whilst providing a flush finish on the underside of the panel, meaning that minimal surface finishing is required after installation. Like all self clinching fasteners they are installed using a parallel squeezing action, so require access to both sides of the panel. Flush Head Studs for Stainless Steel are available in a range of thread sizes and lengths, manufactured from hardened 400 series stainless steel and are suitable for installation in ductile stainless steel with a recommended maximum hardness of 92 HRB. Flush Head Studs for Stainless Steel can also be supplied with a dog-point thread lead-in to aid component assembly.

Dimensional Data Installing 400 series parts into hard stainless steel panels Self-Clinching fastener Do’s & Don’ts Self-Clinching fastener problem solving guides Downloadable Data Sheet Back

Installation

Self Clinching Flush Studs for Stainless Steel

Type NFH

SELF-CLINCHING FLUSH HEAD STUDS FOR STAINLESS STEEL

Hardened bushing with sufficient wall thickness to withstand applied compression load.

Head Dia. + 1.6mm

Test panel.

Compression rig base.

Push-out testing of Self-Clinching Flush Head Studs should be performed by the gradual application of a load as shown above. Bushing height should be sufficient to allow free downward movement of the stud during testing. The bushing bore must be centred on the head of the stud.

Torque-through testing of Self-Clinching Flush Head Studs should be performed by the gradual application of torque as shown while the test panel is securely held in a vice. The hex nut must be of sufficient grade to resist thread stripping. Torque must be gradually applied until failure is observed. Failure mode may vary depending on fastener type, size, length and the properties of the panel the part is installed into. The fastener may actually fracture instead of the head pulling through the panel. Please note that the torque-through values obtained during this test do not indicate the axial strength of the stud threads, the allowable nut tightening torque or the design loading of the assembled component. Torque-through values pertain only to the amount of torque required to pull the stud through the panel.