FAQ - Frequently Asked Questions
How strong is the adhesive force of a magnetic tape and sheet?
Table of Contents
The adhesive force for magnetic tape and sheet is specified in g/cm² in our web shop. It was measured on a steel plate and represents ideal conditions. For practical applications various parameters need to be considered:
Direction of force
- Magnetic adhesive force (a): At a right angle to the surface the needed strength for separating the magnetic tape from the steel plate is measured. Our adhesive force indications in our web shop always refer to strain from this direction. However, the adhesive force of two tapes together is up to 50% stronger compared to tape and iron, because the tape is an ideal adhesive surface.
- Holding strength diagonal (b):This type of strain happens when you hang up an object (e.g. a picture or a sign) with a horizontal magnetic tape onto another horizontal magnetic tape on the wall. When the weight becomes too heavy, the tape "jumps" to the next but one stripe or will be pushed off the other tape and the object falls to the ground. That happens at a weight of about 80% of the magnetic adhesive force.
- Holding strength parallel (c):The friction of plastic on plastic is not very high. Hence, the adhesive force in this direction is only about 40% of the indication in our web shop.
Adhesive force and holding strength for magnetic tape Magnetic adhesive tape ferrite 20 mm
|Magnetic tape on iron||Magnetic tape on magnetic tape|
|Magnetic adhesive force (a)||102 g/cm² (100%)||150 g/cm² (150%)|
|Holding strength diagonal (b)||25 g/cm² (25%)||80 g/cm² (80%)|
|Holding strength parallel (c)||25 g/cm² (25%)||41 g/cm² (40%)|
Adhesive force and holding strength for self-adhesive magnetic sheet
|Magnetic sheet on iron||Magnetic sheet on magnetic sheet|
|Magnetic adhesive force (a)||80 g/cm² (100%)||120 g/cm² (150%)|
|Holding strength diagonal (b)||20 g/cm² (25%)||64 g/cm² (80%)|
|Holding strength parallel (c)||20 g/cm² (25%)||32 g/cm² (40%)|
A numeric example with maximum adhesive force (Case a)
For rectangular products calculate the area (length x width in cm) and multiply it with our adhesive force specification.
E.g. Magnetic adhesive tape ferrite 20 mm with 102 g/cm²
- At a length of 1 metre: 100 cm x 2 cm = 200 cm² x 102 g/cm² = 20 400 g
- At a length of 2 metres: 200 cm x 2 cm = 400 cm² x 102 g/cm² = 40 800 g
- At a length of 5 metres: 500 cm x 2 cm = 1 000 cm² x 102 g/cm² = 102 000 g
E.g. Magnetic adhesive tape neodymium 20 mm with 450 g/cm² at a length of 1 metre: 100 cm x 2 cm = 200 cm² x 450 g/cm² = 90 000 g = 90 kg
For round products calculate the area (Pi x radius² in cm) and multiply it with our adhesive force specification.
E.g. Self-adhesive magnetic sheet with 80 g/cm²
- For a sphere with a radius of 5 cm: 3,14 x 25 cm² = 78 cm² x 80 g/cm² = 6 240 g
- For a sphere with a radius of 10 cm: 3,14 x 100 cm² = 314 cm² x 80 g/cm² = 25 120 g
A numeric example with holding strength diagonal (Case b)
Task: A piece of magnetic tape Magnetic adhesive tape ferrite 20 mm, 20 mm wide and 200 mm long, is glued horizontally to the backside of an aluminium sign. Another magnetic tape of the same size is glued horizontally to a non-magnetic door. How heavy can the sign be to adhere securely to the door?
Calculation: The magnetic strip has an area of 20 cm x 2 cm = 40 cm². The tape has a maximum adhesive force of 102 g/cm² (according to specifications in the web shop). Therefore, the maximum adhesive force of the entire strip is 40 x 102 = 4 080 g, ergo approx. 4 kg.
For the planned vertical strain between the two tapes you can expect at the most 80% holding strength, ergo max. approx. 3,2 kg.
You should always allow for a generous safety margin. In this case it would be good if the sign didn't weigh more than 2 kg, because the door is exposed to strong vibrations when it is being slammed shut.
If the sign is heavier, we recommend using a second or third strip of magnetic tape, a very wide magnetic tape or a strongly magnetised magnetic tape Magnetic adhesive tape neodymium 20 mm. In extreme cases you can use a self-adhesive magnetic sheet and glue it over the whole backside of the sign. That's what we did with a kitchen timer in the following video.
A numeric example with holding strength parallel (Case c)
Task: Identical to Case b, but here we glue the magnetic tape vertically and centred on the backside of a sign. Instead of 20 cm the tape is only 15 cm long.
Calculation: The maximum adhesive force of the tape is 30 x 102 = 3060 g, ergo approx. 3 kg. For the planned parellel strain between the two tapes you can expect at the most 40% holding strength, ergo max. approx. 1,2 kg.
This is probably not sufficient to attach the sign securely to the door, because it swings open and shut and is exposed to vibrations. The parallel strain of a magnetic tape is therefore not recommended. If you can't avoid it, use several vertical strips of magnetic tape to increase the holding strength or the extremely magnetised tape Magnetic adhesive tape neodymium 20 mm. Or as mentioned above, you can use a self-adhesive magnetic sheet and glue it on the entire backside of the sign.
Other factors influencing adhesive forceThe adhesive force specifications in the web shop require ideal conditions. Material, surface texture and working temperature have a significant influence on the adhesive force of a magnetic tape or sheet.
- The maximum adhesive force can only be achieved on smooth surfaces and on full contact. The tape or sheet needs to be placed flat and directly on the counterpart and must not produce bubbles.
- General factors influencing adhesive force are listed in one of our separate FAQ. Magnetic tapes and sheets can never achieve the adhesive force of neodymium magnets.
- If there is no direct contact to an iron counterpart - a piece of paper in between tape/sheet and counterpart is enough - the adhesive force diminishes rapidly. Magnetic tapes and sheets do not adhere at all to magnetic glass boards, because the distance is too great.