About TNC

Larkin (UK) Ltd are manufacturers of TNC Twist Nut Clips and are equipped with comprehensive range of modern moulding machines. Providing capabilities from 25-250 tons. A number of machines have computer control and automatic colour dosing with full ancillary equipment.

A fully equipped tool room utilizing up to date machining technology and staffed by highly experienced toolmakers, provide a fast and efficient on the spot tool making service.

To achieve the most efficient and efficient tooling solution. We use the latest Visicad CAD/CAM system.

Quality Assurance procedures are carried out in accordance with each customer’s specific requirements. Initially “in progress” and “final inspection” procedures are carried out by Larkin Ltd’s trained and monitored personnel.


The following outlines the specifications for the TNC range of products. There are also a range of tests and product reports available on the Technical Data page


Material Specification – The TNC clip is manufactured from a composite polymide (nylon) alloy, which has similar tensile strength properties as nylon, but with much superior impact strength especially at low temperatures. It will function with no noticeable change in a temp range from -40c to + 140c.

Rigidity and Tensile Performance – In cases of material fatigue, resistance to stress cracking is greater than standard polymides. As with all Polymides, flexural rigidity drops between 20c and 80c. Within this range it is more rigid than a standard P6 polymide. It has nylon tensile properties but with a superior impact strength. This is less than 4% deformation under stresses of up to 40Mpa (Mega Pascals).


Creep – The TNC clip has a high resistance to mechanical stress creep.


Chemical Resistance – Withstands all known solvents, hydrolysis, battery acids, salt solutions etc.


Moisture sensitivity – Has a low moisture sensitivity. It has dimensional stability, stable mechanical properties and better rigidity than standard polymides. It has both stable electrical and vibration properties.


Aging – Has less yellowing at higher temps. Also has good resistance to UV light.


Melting Point and Flammability – Has a melting point of 220c and a UL94 rating of HB. As the clip is generally fixed via channel to masonry or similar noncombustible structures and are adequately spaced at 3-foot centers, there should be no flame spread from one support to another. Under these conditions any toxic emission from the clip would be insignificant.


Physical Pull and Slip Tests

Pull and Slip tests were carried out by an independent testing laboratory. SSD Labs in Derby, England. These tests were performed to give a general indication as to the forces needed to pull the TNC channel clip out of 41mm channel or to cause slippage along the channel.

The tests were undertaken on most sizes of the TNC channel clip from 1/4inch to 21/8inch diameter. All tests were performed with randomly selected from standard production runs and at an ambient temperature of 24c.

The perpendicular pull tests give results in excess of 330lbs. This is a multiple of the weight the clip would be required to hold, at three feet centers under normal conditions.

The slip tests to show movements along the channel and to demonstrate the vertical weight holding capacity of the TNC clip, gave results between 64lbs and 70.5lbs, again well in excess of requirements. A glass filled nylon saddle increased these results to between 110lbs and 119lbs.