Mumbai University > Mechanical Engineering > Sem 5 > production process 3

Marks: 10M

Year: May 2016

• The component designer sometimes includes a recess or a projection in a component to perform a particular function or to satisfy an artistic requirement.
• A molding which has a recess or a projection is called as an under cut moulding.
• The design for these components is more complex than the other components due to difficulties of ejection.

Split Mould:

• It was already discussed that in some component make the cavity insert in two parts.
• Consider a two plate mould for a water connector as shown in fig.(a).
• In this design, the cavity for a connector is directly machined into the cavity plate.
• When the mould is opened, the core can be withdrawn but the projections on the component forms undercuts which prevents its removal from the cavity.
• The cavity form for the same connector machined into two separate blocks of steel as shown in fig.(b).
• These splits cavity blocks are knows as Splits.
• One half of the components form is sunk into each split and during the ejection splits can be opened and components can be removed refer fig.(c).
• There are different methods to incorporate the splits into the mould.
• The simplest methods are to fit the splits into a chase bolstes. But this manual methods of removing and opening the splits increases the cycle time of the mould.

• For complex system, where the splits retained on the mould plate and actuated automatically the following techniques are used :
  • Sliding Splits.
  • Angled Lift Splits.
• In this type of design, the splits are mounted in guides on flat mould plate.
• They are actuated in one plane by using mechanical or hydraulic arrangement.
• The splits are locked in their close position by heel that projects from the other mould half.
• It can be mounted on either moving or fixed mould plate (generally on moving mould plate).
• The principle of sliding splits is shown in fig.
• Fig.(a) shows the splits in its closed positions and fig.(b) shows the splits in its open positions.