15-11-2007

The partnership between Cannon Forma, Belotti and Sirtek, provides a complete Cannon package to the bathtubs manufacturers: from simple single units to complex in-line solutions.

This combination of state-of-art technologies is a real breakthrough on this market : it provides a complete solution to those Companies aiming at the continuous production of standard bath tubs. Using an environmentally friendly technology, all customers willing to start bathtubs manufacturing can get from Cannon the transfer of the know how, from the bathtub design and mould construction to the study of equipment layout and factory needs, including machinery supply and training on product manufacturing, assembly and testing.

• The equipment for reinforcement is supplied by Cannon Afros through Sirtek, with the innovative use of  Polyurethane-based material
• The equipment for mould manufacturing and bathtubs trimming is supplied by Belotti, for many years a Cannon partner worldwide.

Siral, a qualified Italian manufacturer of  sanitary and wellness products has recently purchased from Cannon Forma a new thermoforming machine Luce 2216 to  thermoform rectangular, angular and oval tubs, bathtubs panels and shower trays.

Meeting the customer demand for an automatic and precise process control the machine has been equipped with servo mould table, pyrometer and proportional valves for vacuum, bubble and mould release as well as with various options for a fast change of mould, aperture plate and clamp frame.

The heating system is fitted with small quartz elements individually controlled, for better performance and temperature zoning, to gain the benefit of better thickness distribution, so important for aesthetic and structural performance. Heater banks are driven by electric motor for a fast and smooth movement protecting the quartz elements.

Servo drive of mould table is used in preference to the standard pneumatic system. This facility, which gives infinite control through low to high speed movement, will achieve absolute positional accuracy.  The power is delivered from a specially constructed motor system capable of delivering maximum torque at low rpm.  All positional settings can be stored in a PC, along with general sequential data.  This facility provides various advantages:

• better control of the movements for a smoother product release when the mould descends, ensuring minimum product distortion
• possibility of easily set different start/stop positions of the mould table
• better efficiency of the machine

As top-of-the-range thermoformed bathtubs and shower trays are manufactured from cast PMMA, it is necessary for the mould table and clamp frame to supply a great amount of pressure in order to successfully form the vertical rim around the bath edge. For this reason Cannon bath forming machines are fitted with high power cylinders for lifting the mould table and clamping the material.

Another feature of this Cannon Forma thermoformer is the dual pressure clamping that is the ability to release the clamping force during the heating cycle, allowing the acrylic material to expand freely, releasing in this way any stress and tension, therefore stabilising the part dimension with no waves on the rims. 

Sophisticated heating controls have also the differential heating facility permitting the user to vary or even switch off the power to the heating elements for a time controlled period within the overall heating time. This will allow the material to soak, i.e. let the heat penetrate and therefore achieve a higher core temperature without damaging the surface. This is very important when processing thick materials, especially PMMA, in order to reduce the risk of inducing stress in the material which may manifest itself as hairline cracks on the material surface on a later date.

Automatic sag control allows to achieve superior material distribution and thickness control over the most intricate geometry. In turn this means being able to reduce to a minimum the starting thickness of the plastic sheet.

This concept require a little more investment in equipment of the machine, but allows great savings in plastic material, by far the greatest cost in process. Cannon Forma experience in the field of sanitary ware confirms that the best quality products are obtained by a superior temperature zone control – by varying the temperature of the molten plastic sheet zone by zone – and by controlling the sag during heating i.e. maintaining the plastic sheet horizontally flat.

Heating the sheet while holding it vertically with vertical heaters, a machine concept proposed by other manufacturers, does not allow the same degree of control, as ascending air and draughts caused by the “chimney” effect prevent proper heater zone control and also cause high speed heat loss from the surface of the plastic sheet, with great detrimental efficiency: this is also negative in terms of energy consumption and influences the temperature distribution. These are the reasons why the machines with sag control still represent the winning concept in the field of sanitary ware, especially today since more and more complex shapes are required to match the sophisticated needs of the culture  of well-being in the bathroom.

Reinforced bathtubs and shower trays in Polyurethane are a proven reality. Sirtek has supplied to Valentin, one major French producer of sanitary ware, the 27^th plant.

This plant is composed by a four-station rotary system: bathtub loading/unloading, preheating oven, spraying booth with robot and station for catalysis. The high-pressure PUR dosing unit is a Cannon AG6.

The concept of the system combines minimum floor space, because this technology does not require long oven tunnels, with highest productivity. Operating costs are reduced to the minimum as one operator is sufficient to run the plant.

Another big advantage is that immediately after the reinforcing operation the tub is ready for trimming: therefore a storage for the untrimmed bath tubs is not needed and manufacturing lead time is minimum, thus granting a just-in-time production.

What really makes the difference for the operators is the working environment: no more toxic substances, irritating resins and fibers. The specially developed spray foam respects the norms on emissions, provides high thermal and acoustic insulation, optimum resistance and elasticity, can be recycled and reused as a secondary raw material.

Different types of plants are available, from manual to semi- or fully-automatic systems.

For twenty years Belotti has supplied CNC trimming machines to the major world’s producers of the sanitary and composites fields. A special attention has been paid to develop solutions assuring minimum set-up for model change and protection from dust. Novellini, - European leader in the manufacture of bathtubs, whirlpools, shower boxes and mini-pools - has confirmed its trust in Belotti purchasing their 11^th machine.

The need of the customer was a flexible machine able to trim mini-pools, bathtubs and wooden shower plates. Belotti has therefore developed a CNC machine FLA 5532 (5,500 x 3,200 mm) with rotary table and two independent machining heads. One head is equipped with revolver for a fast cutting cycle and to assure compatibility with other machines, the second head is equipped with an high power electro-spindle and automatic tool change to machine the shower wooden bases.

The rotary table solution grants the exploitation of all machining area, a reduced floor space occupied by the machine and an easy loading/unloading.  The total enclosure reduces the noise level and avoids dust evacuation during machining. X,Y and Z axes are protected  by dust protection bellows.  A dust extraction system with chips collection tanks is also provided.

A special mention should be reserved to the automatic bathtub clamping system. This universal equipment allows for the clamping of different sizes and shapes of bathtubs without the need for jigs thus reducing to seconds the model change set-up and cutting the cost of expensive jigs and the relevant storage and handling.

Belotti provides CNC machining centres for aluminium moulds and wood and for manufacturing resin models.