Composite panels and structures vary widely in their constituent materials. Here, we show the TwinDisk method, and its mechanical principles. We’ve used wood, chipboard, alloy and carbon fibre for our test pieces; on this page, the composite material is a simple wooden panel, with a blockboard core and 3mm plywood skins on either surface.
Bottom R.H. shows carbon fibre with a honeycomb core.
Spreading the dynamic load
The first picture shows the main hole cut through the top skin, down to the inner face of the bottom skin. The top surface then has an extra cut to fit the larger top disk - in this case, 40mm in diameter and 2.2mm deep. The 30mm bottom disk requires a 32mm fitting hole, to allow the bottom ‘slug’ of glue to flow through and around the disk’s piercings for maximum adhesion.
Bonding to the top skin
BigBond is applied to the 5mm wide rebated surface - see picture 3. The top disk of every TwinDisk has three indents, each protruding 1mm from the disk’s surface - the optimum thickness of the 2-part BigBond FS Acrylic adhesive. The indents ensure precise film thickness, low wastage and maximum adhesion. The TwinDisk is then firmly pushed into place. We recommend that any surplus glue is wiped off immediately - initial cure starts within a minute.
Flush fit - or surface glue?
All TwinDisks are of 1.2mm thick stainless steel. If flush fit is required, a rebate of 2.2mm provides the 1mm glue depth. If skin thickness is less than this, the top disk is glued to the top skin leaving a 2.2mm high protruding disk. This method is less efficient, however, at distributing lateral shear stresses
Cut through the top skin
Apply BigBond Acrylic adhesive
Removing core material. For flush fitting, rebate the top skin. Top disks are 10mm larger than the bottom; the rebate provides a gluing surface for the top disk
4-5mm deep into the ‘well’. The hole should allow a 1-2mm depth of glue below the bottom disk - surplus glue is forced through holes and locks disk in place
Glue is applied generously
Press the TwinDisk firmly
to the rebated surface. Rebate is 2.2mm deep; disk is 1.2mm thick, and a 1mm standoff (created by 3 indents in the disk) ensures the correct 1mm depth of the adhesive layer required.
into position. Any surplus adhesive round the top disk should be removed immediately - initial set is 5 minutes.
We make every effort to ensure that the information provided on this page is accurate, we can not be held responsible for any errors, typography or otherwise.
Illustrations are representational of typical styles and designs may vary. Product images should not be used for product specifications. For new applications we recommend that assembly tests are carried out using samples supplied by us.
Contact the Hall-Fast Sales Office for more information on (01623) 551 791
Cut through the top skin
