However, if need to reduce such as Φ16mm to Φ14mm, 16 stations will be better.
2. Length of heater to reduce.
If need to reduce heater within 1 meter, heater factories can choose 12 group reducing machine.
If need to reduce 6 meter heater, 18 group roller shrinking machine is recommend.
Generally speaking, for same diameter in same length, if use more station, quality for reduced heaters will be better than less stations.
3. Quantity of heater to make.
If need to make electric heaters in bulk, take more stations is better.
If only make few pieces for samples, to choose a cheaper machineis also good idea.
4. Budget to buy the machines.
Sometimes money is important to get a machine. However, machine is a long time investment.
Few people buy cheap machine, after use short time, there will be many problem or can not work any more. This will waste time and money, or spend more time and people to maintain the machines.
To buy a quality heater shrinking machine, you can make more nice quality heaters, and use for long time. In this way, you can sell more heaters to earn more money.