Vent Caps :
Most polyethylene Spin Weld Fittings are considered Stock Items. All Spin Weld Fittings can be molded in Polypropylene with 30 Days Lead Time. All Spin Weld Fittings can be molded in Black or any other colors. We request 30 days lead time for special colors. We will mold Special Designed Spin Weld Fittings upon request. Parts can be purchased for Prototype projects at the same price as Carton Price. After prototype work is completed, there is a 50% up-charge on less than Carton quantity. Drive tools for part numbers 73 through 53M, 84 through 83, 50 through 70, #375 & #350 and all the blind inserts have 1/4'' shank. All the rest have 1/2'' shanks.
Please note the following definitions corresponding to Part Numbers for Spin Weld Fittings:
HD - Heavy Duty - Increased Wall Thickness (Industrial Applications)
S - Super Thickness
B - Black
C - Color Tint (Blue).
M - Membrane
DT - Double-ended Thread.
Spin Welding Process
Spin Welding is the process of Friction Welding fittings to Containers or Tanks with high RPM. When properly done the fitting becomes integral with the Container and will become almost as durable as the Container. The fitting and the container must be molded of compatible materials. We mold all of our fittings from a high molecular weight Low Density Polyethylene with additives for good adhesion and toughness. Our fittings are compatible with all grades of polyethylene except Cross Link Materials. We do not recommend Spin Welding for Cross Link parts. Also, we do not advise using Spin Weld Fittings molded from High Density Polyethylene. High Density material does not have long term ESCR capabilities; therefore
Stress Cracking can appear at an early stage.
Please consider the following when Spin Welding:
1) When attaching a Spin Weld Fitting, select an area as flat as possible, where the fitting and Driving Tool can turn freely.
2) With the proper size Hole Saw, drill a hole in the container slightly larger than the pilot on the fitting. The fitting must be able to rotate freely. Deburr edges of the hole, but do not remove material from hole as this may result in the hole being too large for the fitting. Check that the fitting fits into the hole and has approximately 0.04” (1mm) of clearance around the fitting.
a. If the hole is too large this will result in the fitting being difficult to control when spinning and will also result in a lack of contact area between the fitting and the product thus giving a poor weld.
b. If the hole is too small this will result in increased friction, which can cause the following two faults.
i. Reduction of speed in the router, which will result in a lack of heat between the two parts being welded, thus, giving a poor weld, which is likely to fail.
ii. The fitting trying to adhere to the product around its outside diameter rather than on the actual weld faces, thus giving a poor weld, which is likely to fail.
3) On small fittings (1/2'' and smaller) you can use a 1 HP Electric Router. On fittings measuring 3/4'' to 1-1/2'', a 1 to 1-1/2 HP to 2 HP Electric Router is acceptable. On fittings 2'' and larger, we recommend a 3 HP Electric Router with at least 14 amps. On small fittings 1/2'' and smaller, we supply drivers with 1/4" shanks. On fittings 3/4'' and larger, we supply drivers with 1/2" shanks. All electric routers should have 18,000 to 25,000 RPM's.
4) Place fitting pilot in the hole of the container. Holding the Router in your hands and having the driving tool attached to the fitting, turn on the power and apply slight pressure so that molten plastic starts to flow around the outside diameter of the fitting. You will develop a technique as to how to apply pressure. The melting process will only take 2-3 seconds. Turn off the power and keep the driver in position with applied pressure for another 5 seconds. This will ensure a goodbond with approximately 1/4'' molten surrounding the diameter of the fitting.
5) After 1 minute you can apply testing procedures, such as tapping with a hammer or prying with leverage.
6) We do not recommend Spin Welding with the use of a Hand Drill or a Drill Press because you cannot attain the required RPM.
7) We do not recommend Pneumatic Routers although they may have the required HP. They are not able to accelerate the required RPM and will tend to "drag'' and not melt the plastic of the fitting and container in order for the molten plastic to flow properly.
8) Pigment in the plastic fitting will have little or no effect on Spin Welding.