SELF DRILLING SCREWS

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TECHNICS

WHICH SCREW FOR WHICH SHEET?

Metal sheet without perforation => SELF DRILLING SCREWS

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You will find the right option for perforated or punched metal sheets => SELF TAPPING SCREWS

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in our catalogue “SELF TAPPING SCREWS“.

TECHNICS

= max. 6,0mm
drilling performance

The drilling point must have fully drilled through the material before the first pitch of screw thread reaches the metal sheet. Refer to the details in the catalogue regarding “drilling performance“ for the determination of the appropriate self drilling screw.

Utilisable thread length (Lg) only relevant for self drilling screws according to DIN/ISO standard. Please note the details (Lg) for each dimension in our catalogue.

P = 2,0mm
Polyamid
Original condition

P = 3,0mm
EPDM - R12/S12
Original condition

  x = max. 1,4mm
Ø 4,2
x = max. 1,6mm
Ø 4,8
x = max. 1,8mm
Ø 5,5
x = max. 1,8mm
Ø 6,3
Ø 4,2 Ø 4,8 Ø 5,5 Ø 6,3 Ø 4,2 Ø 4,8 Ø 5,5 Ø 6,3
  lg (min) (mm) lg (min) (mm) lg (min) (mm) lg (min) (mm) lg (min) (mm) lg (min) (mm) lg (min) (mm) lg (min) (mm) lg (min) (mm) lg (min) (mm) lg (min) (mm) lg (min) (mm)
13 4,3 3,7     3,3 2,7     2,8 2,2    
16 7,3 5,8     6,3 4,7     5,8 4,3    
19 10,3 8,7 8,0 7,0 8,3 7,7 7,0 6,0 8,8 7,2 6,5 5,5
22 13,3 11,7     12,3 10,7     11,8 10,2    
25 16,3 14,7 14,0 13,0 15,3 13,7 13,0 12,0 14,8 13,2 12,5 11,5
32 23,0 21,5 21,0 20,0 22,0 20,5 20,0 19,0 21,5 20,0 19,5 18,5
38 29,0 27,5 27,0 26,0 28,0 26,5 26,0 25,0 27,5 26,0 25,5 24,5
45   34,5 34,0 33,0   33,5 33,0 32,0   33,0 32,5 31,5
50   39,5 39,0 38,0   38,5 38,0 37,0   38,0 37,5 36,5

BI-METAL-SELF-TAPPING SCREW

16 7,0 7,0     6,0 6,0     5,5 5,5    
19 8,5 7,0     7,5 6,0     7,0 5,5    
25 14,5 13,0     13,5 12,0     13,0 11,5    

We recommend the use of screws with washers. x max. = distance from the last complete pitch of screw thread to the bearing area (base).

Lg = distance from the base of head or washer to the last complete pitch of screw thread. U = length of the drilling point and the incomplete pitch of the screw thread.

THREAD PARAMETERS

Drilling point with thread form (B) C

The self drilling screw with the self tapping screw thread - form C – is supplied predominantly for the bonding of metal sheets. The self drilling screw drills (1), shapes (2) and tightens (3) in a single workstep.

Please adhere to the optimal rotational speed setting (RPM) on your drilling machine / electric screw driver. You will find details in the catalogue.

Tapits

The Tapits screw thread with “needle point“ is used for the joining of thin metal sheets, which do not need to be predrilled. The “needle point“ with the steep thread pitch is easy to work with.

THE BI-METAL SELF DRILLING SCREW

A DEVELOPMENT BY GOEBEL

E = Stainless steel A2 (1.4301)

Lg = Serviceable thread length of stainless steel A2 (1.4301)

K = Hardened carbon steel

G = Portion of the thread of hardened carbon steel

The hardened drilling point (K) of carbon steel drills the hole into the stainless steel sheet. The first three hardened pitch of screw thread (G) of carbon steel cut the thread into the stainless steel sheet. The bi-metal self-drilling screw must be screwed into the stainless steel sheet until only the pitches of screw thread of the stainless steel region (Lg) are in direct contact with the stainless steel sheets. In this regard, please note the value (Lg) – serviceable thread length – specified on the catalogue pages.

The bi-metal self drilling screw drills (1), shapes the thread (2) and tightens (3) in a single workstep.

Please adhere to the optimal rotational speed setting (RPM) on your drilling machine / electric screw driver. You will find details in the catalogue.

DIRVE FORMS

The mode of drive of a screw meets a diversity of purposes. On one hand these can make sense for visual reasons, on the other hand, it is usually the mechanical properties that are the reasons for the selection of the appropriate mode of drive.

HEXAGON WASHER HEAD (WITH AND WITHOUT SLOT)

The six outer sides and the washer head allow the practicing of optimum power transfer with the socket wrench (extremely high transmittable torque). The additional slot allows reworking or dismounting.

PAN HEAD CROSS RECESSED (H-PHILLIPS)

The inner drive form (conical drive = self clamping - screw/bit) allows a good transmission of the torque, however, it is lower compared to the hexagon head. The cross recessed drive could be damaged/destroyed in the case of overwinding.

PAN HEAD WITH SQUARE DRIVE (WITH AND WITHOUT SLOT)

The square drive form (conical dThe square drive form (conical drive = self clamping - screw/bit ) a torque, however, it ist lower compared to the hexagon head. The additional slot allows reworking and dismounting. The square drive could be damaged/destroyed in the case of overwinding.

TECHNICAL DATA

TENSILE STRENGTH

The tensile strength indicates the resistance with which the screw opposes axial tension.

Thedefinitions of the tensile strength are the failure parameters of the screw.

SHEARING STRENGTH

The shearing strength defines the resistance with which the screw opposes tangential shearing forces.

The definitions of the shearing strength are the failure parameters of the screw.

TORSIONAL STRENGTH

The resistance to distortion defines the stability of the screw against distortion.

The definitions of the torsional strength are the failure parameters of the screw.

EXTRACTION RESISTANCE

The extraction resistance defines the stability of the screw during extraction from the component.

The definitions of the extraction resistance are the failure parameters of the screw.

PULL-THROUGH STRENGTH

The pull-through strength defines the procedure during which the metal of the component is torn out via screw head.

SURFACE COATINGS

GOEBEL SILVER GL SLIDE COATING

The Goebel silver GL slide coating provides optimum sealing with multifunctional properties, which guarantee excellent corrosion protection and simultaneously reduce the screw-in resistance. It is available in different colours: e.g. silver, black, green and red.

Properties: superior adhesive strength, high hardness with good flexibility, high abrasion resistance, good resistance to weathering, (but not chalk resistant), high electrical insulating property (good protection against contact corrosion), superior resistance to chemicals, superior resistance proven in salt spray test, excellent resistance to sulphur dioxide proven in Kesternich test, excellent resistance to mineral oil, fuels, lubricants and grease, brake fluids, coolants, etc.

*Advise: The GOEBEL-silver-slide-coating provides no UV light resistance, though having a good chemical resistance. When using the GOEBEL-silver-slide-coating in production areas with a strong aggressive atmosphere this can react to certain alkalis and acids, e.g. in vinegar production. This also applies to various cleaning agents and disinfectans. Therefore, the GOEBEL-silver-slide-coating should be tested in the environment before starting construction.

ZINC PLATING (CHROME VI FREE)

By zinc plating the steel is coated with a thin layer of zinc (standard for mounting components 4 – 6 μ) in order to protect it from corrosion. When it has been freshly applied, the zinc layer has a bright sheen and then develops a metallic crystalline appearance for some time. In the course of time it becomes dark grey as a consequence of the corrosion of the zinc, which forms a weatherproof protective layer of zinc oxides and zinc carbonate when exposed to air. If the exposure to air and hence the inlet of carbon dioxide is restricted, undesirable white corrosion will occur.

In contrast to more noble metals such as steel, zinc plays the part of a sacrificial anode, protecting the underlying steel from corrosion until itself is completely corroded. As a consequence of these two material properties, a zinc lay-er of corresponding thickness can provide an economical corrosion protection for decades without any maintenance expenditure (As the thickness of the zinc layer is limited in the mounting components, we recommend supplementary corrosion protection for these parts Goebel silver GL slide coating).

POWDER COATING

Powder coating or powder lacquering is a coating process during which an electrically conductive material is coated with powder lacquer. The powder coating predominantly serves the visual matching of the screw heads / washers to the component. Furthermore, the corrosion resistance of the coated part will be enhanced.

VARNISHING

Varnishing is a coating process during which the fastener is coated with liquid varnish (painting). The varnishing predominantly serves the visual matching of the screw heads / washers to the component. Furthermore, the corrosion resistance of the coated part will be enhanced.

WASHERS

EPDM WASHERS (EPDM = ETHYLENE-PROPYLENE-DIEN-MONOMER RUBBER) ARE UNDETACHABLY PITCHED BY MACHINES ON THE SCREWS

These approved connecting elements ensure secure and sealed fastening and sustainably improve the dynamic strength and stability of a connection.

Standard diameters: 12, 14, 16, 19 mm
On request washers can be supplied in supplementary diameters: 9 - 70 mm
Material: stainless steel (R), steel zinc plated (S), aluminium (A), further materials available.

EPDM washers possess a high resistance to wear and tear (UV and ozone resistance as well as a high thermal resistance), weathering (resistance to weather and humidity), and heat (temperature resistance from –30° to +130° degrees Celsius). Moreover, they exhibit a high resistance to hot water, steam, cleaning agents and detergents. Resistant to diluted acids and brake fluids on a non-mineral oil basis. Not resistant to petroleum products!

POLYAMIDE WASHERS (PA 6.6)
ARE UNDETACHABLY PITCHED BY MACHINES ON THE SCREW

Polyamide possesses the following properties (PA) 6.6: Physical properties:halogen free, flame resistant and self extinguishing.
Colour: natural
Dimensions: 2 mm thickness x 10 mm outer diameter
Customer and laboratory tests have shown that only PA washers with a thickness of 2 mm x 10 mm outer diameter perform a reliable sealing function.
Mounting temperature: -10° to + 85° C
Service temperature: -40° to + 85° C
Resistance to UV radiation: good (approx. 12 years / Central Europe)
Chemical properties:
Excellent resistance to

  • Alkalis
  • Oils
  • Lubricants, grease
  • Oil products
  • Solvents

Limited resistance to

  • all kinds of acids

No resistance to

  • phenol

Both washer types perform a sealing function. EPDM washers possess a greater bearing area/ diameter. The PA washer is directly exposed to weathering (for example UV radiation). The steel and stainless steel washers, which are mounted above the sealing EPDM washer, protect the EPDM and prevent direct exposure to weathering. They seal better than polyamide washers because the metal is more rigid and the EPDM is more flexible.

Note: Polyamide washers could burst in the case of high contact pressure. A protruding burr from the sheet could cause damage / cracks in the polyamide washer. Hence the sealing function is no longer guaranteed.

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