Precision Casting

Precision Casting Process

Mar 10,2016

precision casting

Low temperature wax wax injection process specification

1 1:1 preparation of paraffin wax and stearic acid (concentration) ,formulated wax does not allow mixed with water and other dirt
2 Preparation of insulating cylinder of wax and wax chips by 1:2 (concentration) in fully on wax paste mixer mixing; which temperature setting are between 60~65℃, wax paste needs to has a certain degree of mobility, fine and smooth, no fragments.
3 Controlling shrinkage of wax: :wax injection Diameter 100 millimetre ,shrinkage of wax needs to be control I between 0.9~0.11%, Check once a day
4 Material temperature control of wax, Wax melting cylinder temperature set at 90 ± 5 ° c, not exceeding 95 ° c; insulation cylinder temperature set at 80 ± 5 ℃; wax injection insulation cylinder temperature is 48~50℃,. Wax injection nozzle temperature control within the scope of 54~60℃.
5 Wax injection process parameters Injection pressure 0.2~0.4Mpa, 1-3 minutes holding time, process parameters selected according to size and wall thickness and the structural condition of the wax,
6 For the wax with a blind hole, for ease of extracting core, allow tie to wear 1~2 at the thick diameter 3~5mm hollow, then with red wax on the patch.
7 Clean the mould on the joint surface regularly, to ensure that the wax pieces size precision
8 Wax cooling water temperature control between 20~25℃

Inspection and repair of wax

1 Wax must clear them one by one, in addition to sewing, burrs and dirt.
2 Patch wax allows the use of red wax, but must ensure that the surface finish
3 Wax geometry in each sampling during production, but the wax 100% required inspection of critical size requirements.

tree assembly

1 According to technological requirements, select the appropriate model and set of tree method for group trees.
2 Welding wax requires neat, spacing well proportioned, the interval should be not less than a finger.
3 When welding to prevent cold solder joint, wax tumors to shave

Small workpieces by way of artificial wax type of piece by piece welding sticking above the water flow with investee trees investee which are assembled into wax lost wax casting and clearance works one of the most time consuming steps in investee group tree at the time of using a flat-iron stem or base plate of hot melt and wax investee be bonded. Points to note when Assembly is as follows

1 Multiple wax to be assembled into a group of part.
2 Assembly should make the wax to melt easily along the trunk or base out of 
3 The Assembly of finished products should be the first solidification casting pool final solidification
4 After casting, solidification piece easily from the trunk or base cut

Slurry preparation

Staining sand pulp and hung operation

James should stir the slurry before hanging, modules are then slowly deep into a slurry to the module on the basin margin, remove the module with a brush or compressed air to a sharp corner, button holes, narrow and hard coated parts brush (or blowing) again, repeat this process as painting hanging 1~2 times

Group tree first washed with acetone or alcohol, release agents, such as oil on the surface ,then,immersion into binders and refractory bubbles into a slurry of micro-powder drops  excess grout and shower of sub fire Coffea ,  this operation focused on uniform slurry in wax-coated and does not make bubbles on the surface attachment, persistence
many times repeatedly just like this until you get the thickness of your scheduled, the number operations and thickness of the ceramic shell depending on the workpiece size and weight 。 the thickness shall be capable of supporting cast molten metal weight and make pressure without rupture.

First layer of pulp using the filler with more high-viscosity  the second and after pulp with low viscosity, the temperature of barrels kept in 22~25℃  to prevent pulp slurry ageing.

Dewaxing and sintering

Method used on the industrial ,is take groups tree in high pressure vessel ,locking , with 150 ℃ steam ,the wax melting and outflows rapidly; sintering processes are intended to make a small amount of wax on mould surfaces burning out , enhance the strength 。sintering temperature between 700~1100℃ 

Shock shell

to be natural cooling on the ground.

to get cooled mode on the table and make sure the table pad with board

Opens the pneumatic valve  continuous vibration mode 5~10s till its surface shell remove

Note condition

You must wear protective equipment such as gloves, overalls .pay attention to safety
Generally, do not use water cooling ,for emergency goods or samples , flush mode are available to makes it rapid cooling

Ball blasting

modes of the shell hanging on the rack, hanging neatly in the order,  attention to keep balance to  prevent embryo fall injuries
hooks into the blasting machine until contact with the blasting machine rotary table
Embryos should handle with care to prevent damage hair germ
Steel shot diameters 0.2mm
Shot time depending on cast size, shape, shell and oxidation are not allow to stay
Steel shot sizes affect the quality of surface and cleaning efficiency, ball diameter maximum must be not greater than 0.3mm


Cast gate allowance<2㎜
For security reasons, keep cutting machines idling for two-minute , cutting disc rotating should guarantee the smooth running


Residual height; flat <1 mm, arc <0.8 mm
Install the sanding belt and idle for minutes,make sure equipments are in good working condition.

heat treatment (outsourcing)

The purpose of heat treatment::grain refinement, the Elimination of widmanstatten and casting stress
To prevent annealing of castings surface oxidation during high temperature,need to use iron boxes, sealing and annealing
To prevent the casting surface decarburization, when boxing, the casting should be inserted with charcoal and keep sealed