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I. Why is it necessary to raise the screw barrel?
I.1 What is screw barrel raising?
Raising the screw barrel means increasing the screw diameter compared to the current axis of the machine. For example, the Sumitomo SE75D plastic injection machine, the current screw diameter is 28mm. Now the new screw cylinder design with a diameter of 36mm (screw and cylinder diameter changed from 28mm to 36mm) is called screw barrel raising.
I.2 Purpose of raising the screw barrel
Raising the screw barrel will increase the maximum amount of plastic injected in 1 cycle, for example, the Sumitomo SE75D screw cylinder set with diameter 28 has a maximum injection volume for a cycle of 61 grams (based on GPPS plastic), then after raising D36 barrel can spray up to 100 grams (based on GPPS plastic)
➜ Increase the technological capabilities of the molding machine, meeting molds that require more plastic than the original design of the machine.
II. How to raise the screw barrel
II.1 Information needed to raise the screw barrel
🔹 Machine model information, current screw diameter: From this information combined with looking up the press manufacturer's catalog, we will have all the initial parameters.
🔹 Information required to be changed: The purpose of raising the barrel is to increase the maximum volume of plastic that can be sprayed in 1 shot. Therefore, you need to know the maximum volume for the correct shot you desire.
🔹 Fountain journey: Determine the maximum distance the station can move away from the stationary face.
II.2 Procedure
🔹 From the initial information, calculate the diameter that needs to be increased according to the formula
In there:
D2: screw diameter after raising the barrel.
D1: current screw diameter
M2: Maximum volume of one shot after raising the barrel
M1: Maximum volume of a current spray shot
The final diameter must be rounded up from the calculation above.
🔹 New screw cylinder design: Based on the type of plastic and product to be produced, the assembly parts and the current screw cylinder set will be designed. See more articles about screw cylinder design.
The length of the new design will be longer than the current screw cylinder set.
🔹 Determine what dimensions the machine must meet with the new length of the screw cylinder set, and then make changes to requirements with:
- Fountain jet position
- Hydraulic rod
- Cover
- Heater, Sensor
🔹 Carry out production and installation
III. Points to note when raising the screw barrel
III.1 Increased screw diameter
Normally we will see that the higher the screw diameter, the better because in theory, the larger the maximum amount of plastic for 1 shot, the higher the machine's ability to respond to the amount of plastic in 1 shot
However, when raising the screw barrel, the injection pressure and injection speed will decrease accordingly. For example, if the amount of plastic increases by 1.5 times, the pressure and speed will also decrease by 1.5 times
When pressure and speed are reduced, product quality will be affected, so it is necessary to consider whether reducing injection pressure and speed will meet the required product quality.
III.2 Maximum plastic content and actual product plastic content
To ensure stable product quality, normally the amount of plastic needed for 1 molding shot will be in the range of 30% - 80% of the maximum amount of plastic.
III.3 Select screw barrel lifting unit
Raising the screw barrel requires calculating and comparing many different parameters. The ability to design the screw is an important factor, so in-depth expertise is required to be able to come up with an effective design.
ASG Vietnam Engineering Company Limited is a long-time company in the industry providing screw cylinders for plastic injection machines, understands the design secrets of screw cylinders and has many years of experience providing screw barrel lifting services. Customers feel secure and satisfied.
