Water Glass Investment Casting

Investment casting, also known as lost wax casting, includes processes such as pressing wax, wax repairing, tree forming, dipping, wax melting, molten metal casting and post-processing. Lost wax casting is to use wax to make a wax mold of the part to be cast, and then coat the wax mold with mud, which is a mud mold. After the clay mold is dry, put it in hot water to melt the inner wax mold. Take out the clay mold that has melted the wax mold and then bake it into a pottery mold. Once roasted. Generally, the pouring port is left when the mud mold is made, and then the molten metal is poured from the pouring port. After cooling, the required parts are made.

After more than ten years of precipitation, Qinhuangdao Zhongwei Precision Machinery Co., Ltd. has rich production experience in Water glass investment casting, lost foam precision casting, silica sol precision casting, and shell sand casting. We expect manufacturers from all over the world to consult and negotiate business.

Product Description

Bucket tooth water glass lost wax castingBasic situation

1. Implementation standards: The company strictly implements ISO9001 & TS 16949 certification.

2. Product material standards: ISO, GB, ASTM, SAE, ISO, EN, DIN, JIS, BS

3. Main processes: sand casting, silica sol investment casting, water glass investment casting,shell casting,deburring, sand blasting, machining, heat treatment, leak testing, surface treatment, etc.

4. Available materials:

Carbon steel, alloy steel, stainless steel, gray iron, cast iron, cast steel, cast aluminum, cast copper, etc. can be customized according to customer requirements.

Water Glass Investment Casting Process

Mold making - mold repair - wax module tree - shell making (multi-layer repetition) - dewaxing (recycling) - roasting - smelting and pouring - sand cleaning - cutting - grinding gate - Finishing - Inspection - Warehousing.

Investment Casting Production Process

1. Making a Wax Model (Molding)

Molding is to press the wax material into the mold cavity, cool it and take it out to form a wax mold.

Medium Temperature Wax

Wax injection machine to make wax model

Wax injection machine

2. Mold repair

Repair some appearance defects on the surface of wax mold, such as batch seam, wax injection nozzle, flow pattern, etc.

3. Group tree welding

Group tree welding is to weld the repaired wax mold to the pouring system according to the process card.

Group tree welding

4. Making the mold shell (shell making)

The shell-making process is an all-silica sol process (due to environmental protection issues, the water glass process has been phased out), that is, the prepared silica sol coating is first dipped on the surface of the wax mold, and then sprinkled with refractory sand. Dry and harden under humidity, thus forming a dense refractory coating on the surface of the wax mold, and then repeating the process 5-6, and finally forming a silica sol mold shell with certain strength and refractoriness.

Shell making process

The key process of precision casting in this process, quality assurance, needs to pay attention to the uniform sanding of the coating, and strictly control the viscosity of the coating, the particle size of the sand powder, and the temperature and humidity of the workshop.

5. Dewaxing

Dewaxing is to melt the wax in the mold shell through high temperature steam and then discharge it, so that a mold shell with a cavity that can be cast and formed is obtained.

Dewaxing process

6. Shell roasting

The shell roasting is mainly to burn off the residual wax and moisture in the mold shell. At the same time, the precision casting is poured in the red shell state, and the mold shell is usually roasted at about 1000 degrees for 1-2 hours.

Pay attention to continuous roasting. If the heat dissipation conditions of shell roasting are not good, the bottom needs to be padded.

Shell roasting

7. Melting and pouring

Ingredients are made according to the material and composition of the product, then molten steel is smelted, and the slag removal spectrum is tested. After the composition is qualified, it can be poured. It is necessary to pour the molten steel into the mold shell in strict accordance with the requirements of the process card in the red shell state to form a gradual blank.

Smelting and pouring

8. Sand clearing and shelling

After the poured product is sufficiently cooled, use manual (hammering) or vibration shelling machine to separate the mold shell from the casting to obtain the casting.

clear sand

After preliminary sand cleaning by hand, a shot blasting is performed, so that the shell on the surface of the casting blank is basically removed.

9. Cutting

Cutting is to separate the casting products on the module from the gating system. All precision castings are cut by plasma. Pay attention to the remaining gates not too long. The key is not to cut the casting body.

Plasma Cutting Riser

10. Grinding gate

Grinding the gate is to remove the remaining gate root on the rough casting after the gating system is removed. It is mainly ground by grinding wheel grinding or abrasive belt grinding. This process is divided into initial grinding and fine grinding. Be careful not to damage the grinding. Part body.

Grinding gate

11. Finishing

Finishing is mainly to repair some appearance defects on the surface of castings, such as sand holes, slag holes, flash burrs, deformation, etc. The main methods are welding repair, grinding, correction and shot blasting.

Finishing

12. Inspection and storage

The finished castings are sent to the quality department for size and appearance inspection, and they can be packaged and put into storage after passing the test.

Inspection and warehousing

For the first batch of samples and products specially requested by customers, we will conduct 100% penetrant inspection, and the rest without special requirements are not subject to random inspection.

Development Trend of Investment Casting

● Larger and thinner: At present, the maximum profile size of investment castings can reach 1.8m, while the minimum wall thickness is less than 2mm, and the maximum casting weight is close to 1000kg.

● More precise: Investment castings have become more and more accurate. The general linear dimensional tolerance in the ISO standard is CT6-9, and the special linear dimensional tolerance can be larger than CT3-6. The surface roughness value of investment castings is also Smaller and smaller, can reach Ra0.8um.

● Stronger: The performance of castings is getting better and better due to the improvement of materials and the advancement of process technology. For example, the working temperature of turbine blades used in aircraft engines has been increased from 980 °C to 1200 °C; the application of hot isostatic pressing technology has improved the high temperature and low cycle fatigue properties of nickel-based superalloys, titanium alloys and aluminum alloys produced by investment casting by 3 to 10%. times.

Post Casting Process

1. Heat treatment: annealing, carbonization, tempering, quenching, normalizing, surface tempering

2. Processing equipment: CNC, WEDM, lathe, milling machine, drilling machine, grinder, etc.;

3. Surface treatment: powder spraying, chrome plating, painting, sandblasting, nickel plating, galvanizing, blackening, polishing, bluing, etc.

Moulds and Inspection Fixtures:

1. Mold service life: usually semi-permanent. (except for lost foam)

2. Mold delivery time: 10-25 days, (according to product structure and product size).

3. Tooling and mold maintenance: Zhongwei is responsible for precision parts.

Quality Control

1. Quality control: the defective rate is less than 0.1%.

2. Samples and trial run will be 100% inspected during production and before shipment, sample inspection for mass production according to ISDO standards or customer requirements

3. Testing equipment: flaw detection, spectrum analyzer, golden image analyzer, three-coordinate measuring machine, hardness testing equipment, tensile testing machine;

4. Provide after-sales service.

5. The quality can be traced back.

Application Of Water Glass Lost Wax Casting

Trains and railways, cars and trucks, construction machinery, forklifts, agricultural machinery, shipbuilding, petroleum machinery, construction