Rotary Friction Welder Plastic Spin Welding Machine of Frictional Rotation Fusion Equipment for Nylon_PP_PE Circular/Round Parts

02: Introduction of thermoplastic spin welder

The process of thermoplastic spin welder uses heat generated by rotational friction at the joint line to weld thermoplastic parts with rotationally symmetric joints, the thermoplastic spin welder applied pressure axially while rotating one part against its stationary mate, and the resulting generates heat that melts the parts together

03: Application

Thermoplastic spin welder can weld any circular plastic parts made out of thermoplastic, especially for Nylon, PP and Polyethylene Group, Water Filter, Cups, Cream Jar, Hair Oil Bottle, Container, Casserole, KEEPLEADER™ Technical team can work customized spindle and bottom fixture for various application

04: Thermoplastic spin welder process advantages

Ability to weld parts with a circular joint that are not easily welded by ultrasonic welder

Relatively fast cycle times when compared with other methods

Compatible with most thermoplastics

Ideal for welding of PP and PE materials

Ability to weld several dissimilar materials

No Consumables, fumes, or emissions

High strength, hermetic welds or typical

Heat confined to weld interface

Easily automated

Low cost, quick change tooling

Low maintenance

Low power consumption

05: Joint Design consideration

Thermoplastic part joint must be on a circular axis

Joint design should allow for adequate collapse distance

Final orientation of thermoplastic part if necessary

If at all possible the upper part would be designed for use with drive feature, place for upper tool grasp welding parts

The Joint area must be designed so that there is no other part contact interface

KEEPLEADER™ intelligent assembly solution offers no charge feasibility study and joint design review of your assembly

06: Control parameters

There are several primary process control parameters that affect weld quality, they are the surface velocity of the weld joint, press or axial speed, weld depth, and hold distance and time

07: Surface speed

For a fixed rotational spin speed (RPM), linear surface speed increases with weld joint diameter, for a fixed weld joint diameter, surface speed increases with motor RPM, smaller diameter thermoplastic parts therefore usually require more RPM than large parts of the same material, if the surface speed is too low, an adequate amount of heat will not generated to cause sufficient melting, if the speed is too high, excessive heat in the joint could result in material degradation or reduction in viscosity leading to material flow away from the joint 

The selection of the proper surface speed depends to a large degree on the material and joint geometry of the thermoplastic parts being welded, some materials, such as PVC, can be readily welded for a wide range of values, while others require a narrow range, commonly quoted values in the literature recommend using +/- 2 m/sec (79 in. /sec.) as an initial testing value, this can be adjusted up or down depending on the results and part configuration

08: Press (Axial) speed

The press speed affects the amount of contact pressure between the parts being welded, which is required to generate friction heat, the large the speed, the larger rate of heat rise, in combination with the surface speed, press speed must be high enough to cause melting at the interface as opposed to grinding, but not too high as damage the parts, excess press speed can also lead to stalling of the spin motor as more torque is required to maintain constant spin speed

Selection of the optimum press speed depends on the material and joint geometry of the thermoplastic parts, as well as the surface speed, a range for initial experimentation is 0.5 to 2.0 mm/s

09: Welding depth

The determination of the proper weld depth is highly dependent on the application, the weld joint is typically designed for a specific weld penetration, ideally, the weld is sufficiently deep to produce a strong, hermetically sealed assembly, an excessive depth may lead to the formation of flash (materials that is ejected from the joint area during the weld and adheres to the assembly), the drawing out of reinforcing filler material and realignment of the interchain bonds in the weld plane resulting in a weak axial weld joint, and possibly part distortion

Since weld depth affects the joint strength and the amount of flash generated, it is important to design the weld joint properly to meet both requirements simultaneously, the incorporation of flash trap features is recommended to produce acceptable appearance without compromising strength.

10: Hold

During the hold phase, vertical press travel initially brings the molten parts closer together (dynamic hold) and then allows the molten material to solidify (static hold), amorphous plastic will normally take longer to solidify than semi crystalline plastic, the dynamic hold distance is typically a small value compared to the weld distance, an approximate staring point for initial application setup is 10% of weld distance, the static hold time can vary depending on the size of the part, but is usually in the 1~3 second range

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