During injection molding process of thimble, thimble and thimble hole rub against each other. If thimble oil is not frequently applied to thimble (or thimble hole), thimble will burn out or wear, thimble hole will wear out and become larger. Thimble position of product is prone to flare, which affects product quality (or assembly). Sometimes thimble position needs to be processed and needle may even be broken, which hinders smooth progress of production.
Therefore, we must spray thimble oil on thimble regularly for lubrication and protection.

Thimble oil is generally a high-quality guide rail lubricant. Oil film is tough, does not lose, has excellent lubrication, anti-rust and anti-crawling properties. It is used for plastic mold thimble (push rod) lubrication.

If ejection resistance of ejector pin is too large or ejector pin does not retract smoothly during production of mold, ejector pin oil should be sprayed. In addition, it is necessary to assign someone to spray thimble oil on thimble regularly (at least once per shift) every day to provide lubrication and protection.

(1) Before use, first turn thimble oil bottle (tank) upside down, shake it up and down several times to make liquid in the bottle shake even (mix evenly).
(2) When in use, a tube should be inserted into nozzle hole, and bottle body should be tilted (about 60° angle) or vertically upward, so that nozzle and thimble (thimble hole) are kept at a horizontal distance of about 20cm.
(3) Align one end of tube outlet with thimble (thimble hole), press nozzle with your index finger, and spray thimble oil in a "jog" method.
(4) Proper amount of ejector oil should not be sprayed too much to avoid waste or contamination of product.
(5) After ejection needle oil work is finished, ejection needle action (3-5 times) should be carried out in "manual state" to check oil injection situation and effect, and improve it (if it is not sprayed well, it needs to be sprayed again).
(6) Oil on back mold core or oil stains from thimble hole should be cleaned up with cotton cloth.

 

Do not spray thimble oil upside down. When using, avoid contact with eyes, avoid inhaling spray, keep away from fire, and keep air circulation.
(1) Bottles (spray cans) containing thimble oil should not be placed near high-temperature barrels/nozzles and hot melt heads to prevent thermal explosions.
(2) After ejection needle oil is finished, or when it is not in use, tube should be removed in time, cover should be closed, and it should be sent to specified place for safekeeping.
(3) Bottle with thimble oil should be placed in a cool and ventilated place, avoid direct sunlight or exposure to an environment where temperature exceeds 50℃.
(4) After use, do not throw empty bottle into the fire or pierce it.
(5) It is strictly forbidden to spray thimble oil on the surface of flames or hot metal objects (such as high-temperature barrels, fire guns, etc.).

8kg gimbal of automatic washing machine is an important part of top of inner drum of automatic washing machine. Product picture is shown in Figure 1. Maximum size of product is ø474.60 mm * 27.64mm, average thickness of plastic part is 3.46 mm, material of plastic part is PP+GF8, shrinkage rate is 1.013, and weight of plastic part is 584 grams. Technical requirements for plastic parts are that there must be no defects such as peaks, injection dissatisfaction, flow lines, pores, warpage deformation, silver streaks, cold materials, jet lines, bubbles, etc.

 

Figure 1 Product picture of 8kg gimbal for fully automatic washing machine
Adding 8% glass fiber to plastic parts can increase wear resistance and fatigue strength, can increase electrical properties. It can be seen from Figure 1 that plastic part is shaped like a big circle. Inside the circumference, 2 circles of circular bone positions and 24 radial reinforcement ribs are designed along radius, and 3 screw holes are evenly distributed along circumference.

 

 

Size of plastic part is large, and mold design cavity layout is 1 cavity. Glue position of fixed mold part is directly out of mold base, movable and fixed mold circular insert is an inlay structure. Mold base is a non-standard mold base DDI7070. In order to increase clamping area of moving and fixed molds, increase stability of mold, a balance block is designed at four corners of mold base and fixed on the side of movable mold. A taper positioning block is designed at the center of four sides of mold base to increase accuracy of mold clamping. See mold design drawing 2.
Round plastic parts made of PP material are prone to deformation during injection molding. Deformation is often related to way of glue feeding. When gate is selected in the center of plastic part, deformation will be more obvious. Therefore, gate of this set of molds did not choose side gate to feed glue from center of plastic part. Gating system is designed with 4 point gates, as shown in Figure 3.
Plastic parts have more bones and have a greater tightening force on movable mold. If ejection is unbalanced, plastic parts will be deformed. For this reason, a push plate ejection is designed. Parting line between push plate and mold core is 0.3 mm from inner edge of product to avoid friction between push plate and movable mold core, as shown in Figure 4.
Water transportation design of movable and fixed molds fully considers uniform cooling of mold. Fixed mold is designed with a circular arc-shaped straight-through water, multiple ponds are designed on loop to speed up cooling efficiency. Movable mold also designed an arc-shaped straight-through water, and designed multiple ponds on loop. In addition, outside shape of plastic part, movable mold is designed with a hexagonal shape for water transport.

 

 

Figure 2 Full-automatic washing machine 8 kg gimbal mold diagram      

    

Figure 3 Gating system design    

        

Figure 4 Push plate parting line     

 

 

Figure 5 Physical image of mold