Bumax Hard

Bumax Hard is a group of acid-proof,  self-tapping screws which can simply cut threads in stainless steel an carbon steel sheets. Bumax hard exhibits excellent Surface hardness and are made out of the same high quality material as Bumax 88. Bumax Hard is a great and cost efficient soultion for fitting sheet metal.

 

Bumax Hard Taptite is a thread-forming screw which forms its own thread during assembly due to its trilobular shape, its conical entry thread and its excellent Surface hardness. Suitable for assembly in structural steel and cold rolled stainless steel with hardness up to 200HV.

 

Taptite geometry

 

 

 

Torque and strength for Bumax Hard Taptite 

Class M3 M4 M5 M6 M8 M10
Tightening torque Nm Hard Taptite 1.3 3 6 12 25 49
Thread cutting torque Nm Hard Taptite 0.7 1.8 3.5 8 15 28
Breaking torque, min Nm Hard Taptite 4.5 7.9 13 20 30 52

 

 

Optimal hole diameters for Bumax Hard Taptite. Drilled or punched holes depending on material thickness and thread

Thread / Thickness⇒ 0.1-1.5 1.51-2.5 2.51-4 4.1-6.5 6.6-10 10.1-15
M3  2.7  2.8  2.8  2.85
M4  3.65  3.65  3.7  3.75  3.8
M5  4.6  4.7  4.7  4.75
M6  5.5  5.6  5.6  5.65 5.7
M8  7.5  7.5  7.6  7.7
M10  9.3  9.3  9.4  9.5

 

 

Bumax Hard sheet metal screw (ST) is a self tapping screw with ST thread. Designed  for fitting to sheet metal and profiles of carrbon steel, as well as stainless steels.

 

Optimal hole diameters and plate thickness (T) for Bumax Hard ST thread.

T ST2.9 ST3.5 ST4.2 ST4.8 ST5.5 ST6.3
<0.56  2.2  2.6
0.56-0.63  2.3  2.7  3.2  3.7
0.64-0.75  2.3  2.8  3.2  3.7  4.3
0.76-0.88  2.4  2.8  3.2  3.8  4.3  4.9
0.89-1.25  2.4  2.8  3.3  3.8  4.4  4.9
1.26-1.38  2.5  2.8  3.5  3.9  4.5  4.9
1.39-1.75  2.6  2.9  3.8  3.9  4.6  5.0
1.76-2.25  3.0  3.8  4.9  4.7  5.2
2.26-3.0  3.2  3.9  4.1  5.0  5.3
3.1-4.0  4.4  5.1  5.8

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