91. Name the methods used for actuation of stripper plate?
- Tie rod actuation
- Length bolt actuation
- Chain actuation
- Direct actuation
When a hot plastic cools inside a mold, it contracts by an amount depending on the material being processed and the final product is smaller than the mold size is called shrinkage.
- Increase of material temperature.
- Increase of mold temperature.
- Increase in wall thickness.
- Low injection pressure .
- Low melt and mold temperature
- High injection pressure
- Long injection time
- Presence of filler materials and its content
A molding which has a recess or projection is termed as an undercut molding
96. What do you mean external undercut?
Any recess or projection on the outside surface of the component which prevents its removal from cavity is termed an external undercut
97. Name the methods of split actuation?
- Finger cam actuation
- Dog leg cam actuation
- Cam track actuation
- Spring actuation
- Hydraulic actuation
98. How can we calculate finger cam length?
Finger cam length =(M/Sin Q) +(2c) l Sin 2Q
M= split movement
Q=angle of finger cam
99. Where we use side core and side cavity ?
A side core is a local core which is normally mounted at right angled to the mold axis for forming a hole or recess in the side face of a molding. The side cavity performs a similar function to the side core, in that it permits the molding of components which are not in line of draw. This element allows the components with a projection or projections on one or more of their side faces.
100. Where we use form pin straight action method ?
For the components which has internal undercut on one side of the wall.
101. Where we use form pin straight action method ?
We use form pin straight action method for the components which has internal undercut throughout the wall
102. What is single daylight mold ?
When a basic mold is opened, there is only one space or “daylight “ between the two mold halves. This is called a single daylight mold.
103. Explain about double daylight stripper plate mold ?
A stripper plate mold consists of a fixed plate, a moving mold plate and a stripper plate. There are two day light when opened. This is called double daylight stripper plate mold.
104. What is underfeeding mold?
An underfeeding mold is the one in which the feed system is arranged to feed into the underside of the component.
105. What are the types of injection molding defects ?
Sinkmark, Streaks, Blisters/Bubbles, Weld line, Ejector marks, Cold weld, Jetting, Warpage
106.Define sink mark ?
Sink marks are the localized contractions or the depressions on the surface of the moldings.
107. What is blister or bubbles ?
Hollows created on or in the molded part.
108. What is weld line ?
It is the witness marks of two or more melt flow fronts at their joining zone.
109.What is jetting ?
It is the prominent in-homogeneous snake like strands on the surface of molding.
110.What is warpage ?
Warpage is the deviation of the mold part from its required shape.
111.What is bulk factor?
Bulk factor is defined as the ratio of the volume of the loose powder to the volume of the molded part.
112. What are the types of compression molds?
- Flash mold
- Fully positive mold
- Semi positive mold
- Landed positive mold
113. Write a short note about performs ?
Performs are small pellets or tablets of molding material that are formed to shape in a special performs mold at room temperature. Curing won't takes place only densification.
114. Name the types of transfer molds ?
- Pot transfer mold
- Plunger transfer mold
115. What is die casting?
Pressure die casting is the process in which the molten metal is forced under high pressure into a cavity in a metal disc with in fraction of a second and allowed to solidify.
116. What are the types of die casting ?
- Hot chamber process
- Cold chamber process
117.Write the differences between hot chamber and cold chamber processes ?
|Hot chamber process||Cold chamber process|
|The plunger and cylinder are submerged in the molten metal in the holding furnace.||Molten metal is ladled into the cold chamber.|
|After shot, plunger is forced the molten metal through the nozzle.||After ladling, the plunger advanced to force the metal in to the die.|
|Since both plunger & goose neck are submerged in the molten metal, it refills automatically when the plunger is withdrawn.||Each time, we have to ladle the molten material in to the chamber.|
|For casting metals that melt at lower temperature such as zinc and lead.||For casting metals that melts at high temperature such as aluminum, magnesium and brass.|
118. What are the types of die casting defects ?
- Cold defects
- Hot defects
- Miscellaneous defects
119. Example for cold defects ?
Lack of fill, cold shut, severe chill, chill, flow lines
120. Examples for hot defects ?
Soldering, cracks, broken part, bent part, heat marks or shrinkage pits.