The T-DRILL method was developed in the 1970s. The idea that pipes and tubes could be branched much more quickly and cost-effectively into end products of greater strength and higher quality was as revolutionary as it was simple, and one of the major inventions in the field.
As the tee is fabricated from the basic tube, no costly T-pieces are needed. Instead of three joints there is only one joint! This saves a lot of time and means considerably lower total costs. The construction also makes the tube stronger and provides for better flow characteristics.
Pipe branching - i.e. connecting a branch pipe to a run pipe - using T-DRILL method is also called collaring. The joint can be completed by brazing (= lap joint) or by welding (butt joint).
For the lap joint process, a round hole is drilled in the pipe wall using a collaring head. After the tube wall is penetrated, two forming pins are extended from the drill bit. The collaring head then automatically withdraws from the main run pipe and forms a collar in readiness for the branch tube. The branch tube is located within the collar and finally the joint is completed by brazing. A brazing fixture, a bead or dimple (depth stop), on the tube end ensures that the tube will penetrate to the correct depth on the run tube.
The required collar height (i.e. lapping distance) must be three times the branch tube wall thickness to get the maximum joint strength. Normally lap joints are used on small diameter tubing applications, such as used in the HVAC, automotive and other industries.
The time needed for making an outlet using the T-Drill method varies from seconds to minutes, depending on the tube diameter and pipe material used. The complete collaring process is carried out on the outside of the pipe, as opposed to traditional methods in which tools are inserted into the pipe, which makes the tooling difficult to locate when long lengths of pipe are required.
ADVANTAGES OF T-DRILL METHOD
Production cost reductions up to 80%
No costly inventories
Less wasted material
Remarkably faster through-put times
Improved product strength, flow and brazing characteristics
Only one brazed joint instead of three
Applicable to almost all malleable materials including stainless steel, CuNi, aluminium alloys and copper