Computer Controlled, Traveling, Twin hoist, Beam Crane
This type of crane is in widespread use and is very reliable and is well suited to the industry.
Gongda Galvanizing supplies a computer assisted add on to automate crane functions. This product delivers excellent cost and quality benefits.
We offer an integrated unit which works with little human supervision other than the selection of the programme for the goods being worked.
Once the programme is selected the residence time in each bath, the rate of entry and withdrawal and the angle of entry and withdrawal are set.
The objective of this equipment is to
◆ Standardize operations to eliminate variations from one dip to the next and to thus produce a more consistent product and to protect baths from contamination
◆ Allow the galvanizer to optimize all aspects of the process related to the crane to ensure that dip times, drainage times and angles of immersion and extraction are exactly the best and to thus reduce costs, increase productivity and improve quality
The benefits:
◆ Reduced materials costs particularly zinc where correct withdrawal angle and speed assists in control of the coating weight
◆ Consistent product as the conditions for each dip are close to identical
◆ Incremental improvement as reliance can be placed on results
◆ Reduced management input to achieve control of the process
◆ Increased management confidence in the manufacturing procedure
Savings in your manufacturing costs pay for this equipment in between 6 months and 1.5 years
Examples of Benefits Obtained by Automation of the Crane
1. Correct drainage of work out of pickle, rinse and pre-flux reduces the carryover of ferrous iron into the kettle
With random crane use the volume of liquid carried forward on the work is as high as 10 Liters per tonne. This is reduced to 2.5 Liters per tonne with auto crane control or a reduction of 7.5 Liters per tonne.
◆ Thus 7.5 Lts per tonne remain in the pickle tank
◆ 7.5 Liters per tonne of acid do not have to be disposed of from the rinse
◆ The rinse is not so acid and thus does not dissolve further Fe from the work only for this iron to be removed in the waste treatment plant or carried forward into pre-flux
◆ The pre-flux is not so acid and thus does not dissolve so much iron to be carried forward into the kettle
If we then look at a good pre-flux system with 2 g/l Fe++ this brings about a reduction of 7.5 Liters per tonne or 15 gms Zn per tonne.
Zinc combines with Zn in the approximate ratio of 30:1. Thus dross is reduced by 450 gms per tonne. At a Zinc buying price of US$2000 per tonne and a 30% discount for dross we save US$0.27 per tonne
If we look at a poorly managed pre-flux with say 15 g/l Fe++ we save US$2.02 per tonne
If we add all the cost savings they are substantial
2. A high carry over of iron into the kettle ensures a viscous molten alloy
Viscous alloy does not run easily off the work. Over coating results. 30% over coating is common. With US$2000 per tonne zinc and a target of 80 microns and a 100 m2 per tonne area we have an extra cost of US$ 6.8 per tonne
3. Too rapid withdrawal of the work from the kettle
This action causes freezing of the zinc before it has run off adequately. Over coating results. See example 2 for costs