Quality & Precision
On Heat Transfer.
Precision engineered for quality, records are maintained to ensure the repeatability of the set-up and to monitor all processing parameters. A range of in-line and off-line QC checks including, but not limited to, SPC, electromagnetic inspection, microscopic evaluation and testing to destruction are all used to achieve our target of zero external defects.
Select from the options below for more information on our manufacturing and quality control process.
The hardness and mechanical properties of the raw material strip has an affect on the weld process with the edge condition also key to ensure uniform heating from the inside to the outside. Strip is supplied with an even tension throughout the coil and presented flat on a pallet (eye to the sky) fully protected from water contamination.
Our solder coated brass tubes use cartridge brass or 70:30 brass (CuZn30 As) for an optimal combination of strength and formability with an arsenical (As) component to prevent dezincification.
A range of clad aluminium alloys are available with specialist alloys on request. Clad ratios are nominally, 10% but available from 5 to 15% and on one or both sides.
Once the strip is jogged through the mill and running, one of the first processes is to inkjet print the strip with our identifier for traceability.
Production of the tube uses a roll forming process whereby strip material is progressively formed/folded from the outside edge to the inside. Passing through a series of rotating form tools, each pass does a part of the work.
These form tools, running the length of the mill, include both vertical and horizontal rolls that are powered and idle respectively. The design of this tooling is a critical part of the manufacturing process as is a correct and skilful set-up of the mill.
The HF current is delivered through buss bars and into an induction coil. Wound around the open seam tube, the coil is positioned just upstream of the weld rolls. The resistance of the copper coil causes it to heat up and the induced current flows around the formed strip to the open strip edge.
The concentration of the current at the strip edge ensures they are at welding temperature when squeezed together through the weld rolls and a true forge weld is achieved.
Metal oxides are squeezed out of the weld as the edges pass between the weld rolls, forming a weld bead which is removed by scarfing.
Post-forming through powered V-stations provide a stretching and shaping action while the idle H-stations stretch the tube into the desired form.
Non-destructive, electromagnetic inspection of the tube is performed in-process using the eddy check. An alternating magnetic field is induced into the tube causing an eddy current to flow and any change in the flow indicates a defect.
The eddy check inspects the entire run of tube and is set to an alarm with any defect tube directed away from the quality finished goods.
Under factory conditions the exposed surface of the brass tube will react with the atmosphere to produce an oxide layer. Ordinarily, this would result in imperfect solder coverage and adhesion so the oxide is removed using a flux prior to the solder bath. The tube is then evenly coated with solder through a surface tension effect known as wetting.
The tube is then quenched immediately after solder is applied so that the solder is solid before entering final sizing.
The final sizing bed has a series of identical, vertical rolls. They ensure tension throughout the mill and help with final forming. Any bow (lateral curvature) is controlled through bow rolls and the final size stand helps control straightness (longitudinal curvature), as well as fine adjustment or calibration of size.
Tubes are cut to customer specified length prior to packing for despatch.
Our long length tubes are packaged for despatch in export compliant, heat-treated wooden cases, lined with VCI paper to prevent corrosion. Shorter lengths can also be loaded end-to-end with protection in between or in individual cardboard boxes and shrink wrapped onto wooden pallets.
Destructive tests offer an evaluation of the raw material, mill set up and the process. Burst pressure also offers a statistical measure of the durability and reliability of the product in service.