Standard bolt connection
A simple, yet strong joint can be achieved by using a socket head screw, with a square washer, screwed into the core hole of the joining profile (see image on right). A small hole is drilled opposite where the joining profile is to be located. This hole is the access for a hex key to tighten the screw.
This is the standard joint type for the Alusic extruded aluminium profile range of products. It is the most cost effective and commonly used joint type.
The typical cost of this joint is around $0.34 using an M8x20 bolt (084.301.003) and 13×13 washer (084.303.001). And it can normally be assembled in under a minute. A leading competitor’s equivalent connection costs around $3.35 each and can take 3 times longer to achieve.
In some applications, an anti twist device can be used to replace the square washer in the standard connection. The twin tabs on the anti twist device go into the slots of the connecting profile to prevent the joint twisting. A simple and effective solution on the rare occasions it is needed.
Save time & money
The total time taken to complete a Competitor’s standard connection is 2-3 minutes. This, of course, depends on available tooling. Without appropriate tooling being available, it could take even longer. So, if we add this (up to 300% greater) labour cost to the higher material cost of the competitor’s connection, the choice becomes simple.
Also, with the Competitor’s connection, the dimension from the profile end to the centre of the cross bush is critical to the connection effectiveness. If the correct dimension is not achieved with sufficient accuracy, the length of profile effectively becomes scrap. Whereas, with the Alusic connection system if the pilot hole location is not correct then it’s simply a matter of drilling another hole at the correct location. In some cases, the adjoining profile may need to be tapped accordingly, but those cases are quite rare.
No milling or special tooling
The dimension for the pilot hole with Alusic profile is predetermined by the drilling jig (084.818.001) with several millimetres of adjustment from side to side. With the Alusic connecting system there is also the option of self tapping the screw into the adjoining profile as opposed to pre-tapping. This can ensure that the screw has the tightest possible fit to eliminate any possibility of vibration affecting the joint. The potential for a loose joint can also be eliminated with the use of thread locking products such as Loctite. It must be said, though, that the need for either of these is extremely rare because the joint is highly effective in the first place.
To demonstrate some of the labour savings that can be achieved using the Alusic system, a cost comparison exercise was undertaken on the structure shown at the top of this page. The resulting time and motion study estimated the labour saving that could be achieved using the Alusic aluminium system when compared with another high quality European competitor’s profile.
With 350 individual connection points in the structure, a saving of between 300% and 500% in labour costs using Alusic standard connectors is possible. In other words, if using a competitor’s connector that takes up to 3 minutes per connection point, you would require 1,050 minutes or 17.5 hours just to complete the connections on this structure. Then there is the cost of the connector parts themselves at around $1,170.
Using the Alusic standard bolt connection, taking less than a minute each, all the connections could be completed in 5.8 hours. The connector parts would only cost around $120. That is three times faster than the Competitor’s system representing an enormous saving in labour costs alone. This represents a saving of around 11.7 hours, on that structure, and about $1050 in parts.