Operation Of The CTM Varithane Mixing Head

The principle of the new 3 piston mixing head from CTM employs well-known impingement mixing principles via a grooved mixing piston and larger diameter-cleaning chamber, we combine them with a novel and new method of low output dosing control. An active UK patent covers the mixing head’s principle of operation. This first patent is being extended to include a number of regions globally. A second patent is also being pursued that covers a further mode of operation.

The Varithane mixing head is capable of dispensing a maximum of 100 grams per second in ‘continuous pouring’ mode, whilst also being able to achieve a minimum output of 4 grams per second in ‘multi shot’ mode at a ratio of up to 4:1. In addition the dispensing rate can be adjusted to any output in between on a shot to shot basis being fully controlled by the metering unit’s software program.

There is no requirement for altering injector pressure settings or high-pressure pump outputs between operating modes. Unlike other designs of low output mixing heads, mixing ratios of up to 4:1 do not limit the range of low output that is achievable from the Varithane mixing head. Dual hardness /dual density mixing via two mixing chambers is also possible.

The mixing head has several additional features; it is possible to apply considerable injection or dosing pressures at controlled rates without an adverse affect on the quality of component mixing. The mixing head can apply considerable pressure to the reacting mixture thus opening up many possibilities for controlled injection techniques.

A further benefit of the mixing head is the ability to vary output rate during the dispensing phase, this has particular value when producing automotive panel air filters. Over filling in the corners is easily corrected, in addition higher straight-line pouring speeds are possible.

The mixing head can be fitted as part of a multi headed installation and can work with traditional 2-piston L type high-pressure mixing heads.

The high-pressure metering unit required for the mixing head remains largely unchanged being based upon a 50Kg max per minute high-pressure machine, an accurate component flow measurement system c/w an enhanced hydraulic and control software are all of the changes required.

Mixing head reliability is enhanced by an internal pumping action within two central chambers. Lubricant is forced through these internal chambers every working cycle.

A water-cooling chamber is fitted to the main body of the mixing head so as to maintain a steady operating temperature at all times.

The market potential for this type of metering technology is seen by CTM as being potentially very large as it brings solvent free mixing to market sectors that currently must use low-pressure technology because of low output requirements. Variable output during dispense and the ability to apply injection pressure is seen by CTM as possible techniques that could offer new and novel processing possibilities.

Benefits Of The Varithane Mixing Head

• Solvent free micro dosing high pressure mixing technology
• Laminar flow characteristics
• Dispensing range from 1g/s to 100g/s
• Multiple micro dosing mixing head capability
• 1g/s to 100g/s output capability on a shot to shot basis
• Programmable variable dispense rate capability
• Post mixing component injection capability
• Compatible with conventional mixing heads with outputs up to 900g/s
• Ratio capability up to 4:1

Shane Wootton
Director
CTM