Plaster molds, Other Engineering

Assignment Help:

           Plastic molds are made of plaster of Paris (gypsum) or calcium sulphate, talc and silica flour is added in the plaster of Paris to improve strength and to control the time required for the plaster to set. These ingredients are mixed with water and the resulting slurry is poured over the pattern.

           The plaster sets within 15 minutes usually. After the plaster sets, the pattern is removed and the mould is dried at 120°C -260°C to remove the moisture. The mould halves are assembled to form the mould cavity and are preheated to about 120°C. The molten metal is then poured into the mould.

           Patterns for plaster moulding are generally made of Aluminum, thermosetting plastics, brass or zinc alloys. Wood patterns are not appropriate for producing a large number of mould because they are repeatedly in contact with the water based plaster slurry.


Related Discussions:- Plaster molds

Pressure relief valve - aircraft engine, PRESSURE RELIEF VALVE The pres...

PRESSURE RELIEF VALVE The pressure relief valve shown in the figure. controls the oil pressure at the pre-set value demanded by the system. The valve is normally integral with

Static machines, briefly differenciate the moore & mealy machines

briefly differenciate the moore & mealy machines

Series of cash flows in economical engineering, Series of Cash Flows M...

Series of Cash Flows Most engineering economic analysis involve more than a single return occurring after the investment is made. In such cases, the present worth or the futur

Cathode ray tube (crt), Cathode ray tube (crt): Displays of this type, ...

Cathode ray tube (crt): Displays of this type, which are based on the electron beam scanning technique, have been used in aircraft for many years.  They were first used to disp

Control surfaces , Control Surfaces  As with a flight control system...

Control Surfaces  As with a flight control system, a guidance algorithm uses control surfaces to control the behaviour of an airframe.         - Rudder, ailerons, elev

Electronics, explain compensated semiconductors

explain compensated semiconductors

Isdn, Explain the meaning of numbering and addressing in ISDN network.

Explain the meaning of numbering and addressing in ISDN network.

Allowances for pattern, Allowances for pattern : A pattern is always made ...

Allowances for pattern : A pattern is always made larger than the required size of the casting in order to allow for various factor, such as shrinkage, machining, distortion and r

Logic gate - nand gate, NAND Gate; When constructing a NAND gate using ...

NAND Gate; When constructing a NAND gate using transistors as the switching devices, the output often represents the 'inversion' of the "AND" gate. Figure 4 shows an example o

Capital budgeting decisions, Capital Budgeting Decisions The most important...

Capital Budgeting Decisions The most important function of a finance manager is the efficient allocation of its capital. The investment decision of a firm is termed as capital budg

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd