Mechanical parts: investment casting processing 

Mechanical Parts: Investment Casting Processing - Key Parameters for B2B Procurement

Mechanical parts produced by investment casting (WMC) provide accuracy up to IT7 and roughness Ra 1.6–3.2 µm without subsequent machining in critical areas. In our practice, supplying components for the oil and gas sector has shown that a deviation in the chemical composition of the alloy by even 0.5% from the GOST 977-88 norm leads to defective batches of 2000 pieces upon acceptance of incoming inspection. This article reveals the technical nuances of production that directly affect the final cost of owning a part, and not just the price per kilogram of casting.

The industrial casting market in 2026 requires suppliers to be transparent in the value chain. We analyzed more than 40 requests from European and Asian integrators and identified a systemic error: buyers focus on the price of the mold, ignoring the casting yield rate. For complex geometries, this ratio can vary from 45% to 65%, doubling the actual cost of the final mechanical part. Below we will look at how material specifications and tolerances shape the final check.

Technological process: from 3D model to finished mechanical part

The process of creating a mechanical part begins not with melting metal, but with the development of a gating system in CAD. An error at this stage costing $200 is corrected in an hour, while an error in the finished equipment costs $5,000 and two weeks of line downtime. In our production, we use a hybrid approach: rapid prototyping of master models from photopolymer followed by silicone molding for pilot batches of up to 50 pieces. This allows the customer to receive the first samples of mechanical parts 7 days after the drawings are approved.

The key step is applying the ceramic shell. The number of layers directly dictates the surface quality of the future mechanical part. For standard case parts, 6–7 layers are sufficient, but for elements with deep grooves or thin ribs (less than 2 mm), we increase the number of layers to 9–10, using sol-gel technology for the first layer. This prevents the formation of “burnt” - a defect that cannot be removed by mechanical processing without disturbing the geometry.

The model is burned out in autoclaves at a temperature of 160–180°C under a pressure of 6–8 bar. Therein lies a risk that is rarely discussed openly: residual carbon in the mold. If the burning cycle is shortened to speed up shipment, gas evolution occurs when the melt is poured, leading to gas pockets inside the body of the part. We introduced spectral analysis of the furnace atmosphere before pouring, which reduced the percentage of internal defects by 12% in 2025. For the customer, this means the absence of hidden defects that only appear under load.

Metal is poured into preheated molds (up to 800–900°C for heat-resistant alloys). The temperature gradient between the metal and the mold determines the grain structure. Rapid cooling produces a fine-grained structure with high hardness but low toughness. Slow cooling improves ductility but reduces yield strength. The choice of heat treatment mode depends on whether the mechanical part will be subject to wear or shock. Our engineers always request a load map from the client before starting a melt.

The final stage is removing the ceramics and cutting off the sprues. Hydraulic cleaning at 150 bar pressure removes the bulk of the ceramic, but complex internal cavities require chemical etching or corundum sandblasting. Machining at this stage is minimal: usually only facing the reference planes and drilling threaded holes to an H7 tolerance. The use of LVM makes it possible to reduce the volume of metal removed by 80% compared to production from rolled metal, which is critical for expensive alloys such as Inconel or titanium.

Material Selection: Impact of Alloy on Mechanical Part Cost

60% of the cost of a mechanical part is determined by the choice of alloy rather than the complexity of the casting. Carbon steels of type 20L or 35L in accordance with GOST 977-88 are a budget solution for pump casings and valves operating at temperatures up to 400°C. However, when ordering small quantities (less than 100 kg), the price per kilo increases sharply due to the need for separate melting. We recommend consolidating orders of different parts from the same class of steel into one heat weighing 500–800 kg to optimize costs.

Stainless steel grades 12Х18Н10Т (AISI 321) and 08Х18Н10 (AISI 304) require strict control of the content of the ferrite phase. In our laboratory we carry out ferritometry of each batch. Deviation of the amount of ferrite beyond 3–10% leads to a decrease in corrosion resistance in aggressive environments. For customers in the chemical industry, we provide sulfuric acid test reports according to ASTM G28. This is not just a piece of paper, but a guarantee that the mechanical part will not leak after six months of operation.

Heat-resistant nickel alloys (ХН35ВТ, Inconel 718) present the greatest difficulty in processing investment castings. High melt viscosity requires an increase in pouring temperature to 1550–1600°C, which has an aggressive effect on the ceramic mold. The risk of metal interaction with the mold is high, so we use special barrier coatings based on zirconium oxide. The price of such mechanical parts can reach $80–120 per kg, but forged alternatives are often more expensive due to colossal material waste (up to 70%). It is the work with such exotic materials that forms the basis of the company’s competencies.Wuxi Kaisheng Electric Power and Petrochemical Equipment Co., Ltd.. Specializing in the production of heat transfer equipment and components for the oil and gas industry, the company successfully introduces technologies for casting and processing of tube bundles from nickel alloys (N06625), titanium and marine brass C46400. Wuxi Kaisheng's experience in creating ASME high-pressure heat exchangers and corrugated tube bundles confirms that proper alloy selection and process conditions can achieve exceptional corrosion and high-pressure resistance, which is critical for desalination and shipbuilding projects.

Aluminum alloys (AK12, AK7ch) are used for light mechanical parts in the aerospace industry and instrument making. LVM makes it possible to obtain thin-walled structures (1.5–2 mm), which are unattainable for chill casting. The main problem here is porosity. We use vacuum injection molding (V-process) to remove dissolved hydrogen from the melt. The density of the castings reaches 99.5% of the theoretical, which is confirmed by X-ray inspection according to class 2 of the ISO 4993 standard.

* Prices are indicative for batches of 500 kg, valid for 2026. ** CT - accuracy class according to ISO 8062.

Tolerances and surface quality: where casting ends and machining begins

Standard tolerances for investment casting are ±0.1 mm per 100 mm length for sizes up to 500 mm. However, it is important to understand the difference between “feasible” and “economically feasible”. Achieving a tolerance of ±0.05 mm requires the use of precision tooling and a climate-controlled workshop, which increases the cost of the mold by 40%. In most cases, an allowance of 0.3–0.5 mm is left for the mating surfaces of mechanical parts for subsequent turning or milling.

The surface roughness directly depends on the filler fraction of the ceramic shell. The use of electrocorundum with F360 grit makes it possible to obtain Ra 1.6 µm “out of the mold”. This eliminates the need to grind critical sealing surfaces. In one hydraulic distributor project, we saved the client $15,000 per batch by eliminating the surface grinding operation by optimizing the slurry composition.

Geometric deviations such as flatness and alignment are more difficult to control than linear dimensions. Cooling deformation is the main enemy of large mechanical parts. For frames and beds longer than 1 meter, we include technological allowances for deformation in the master model, based on the simulation of the solidification process in the ProCAST software package. Without this measure, the part after machining may shrink in size due to stress relief.

Quality control includes three mandatory stages: visual inspection (VT), penetrant testing (PT) and ultrasonic testing (UT) for critical components. According to the enterprise's internal standard, adopted in 2025, any cracks longer than 2 mm in stress concentration zones are grounds for rejection. We do not use the “brew and forget” rule, since the heat-affected zone of the weld becomes a source of corrosion. It’s better to remelt the part than to risk your partner’s reputation.

Economic efficiency: calculating the break-even point

The transition to mechanical parts from fiberglass is economically justified with a production volume of 50 pieces per year. For a single production, the cost of developing the wax pattern and ceramic mold can be disproportionately high. However, if we consider the full life cycle of a product, the picture changes. Reducing the weight of the part by 20% by optimizing the geometry (which is only possible with casting) reduces the load on the bearings and drives of the mechanism, extending their service life.

Let's compare two options for making a stainless steel pump impeller. Option A: milling from a solid circle. Material consumption: 15 kg per 1 part (utilization rate 25%). Machine hours: 8 hours. Option B: lost wax casting. Metal consumption: 4.5 kg (yield 65%, taking into account the sprues). Machining time: 1.5 hours. With a material cost of $10/kg and a machine-hour of $50, the savings per part is $140. For a batch of 1000 pieces the benefit exceeds $140,000.

Another factor is the ability to integrate functions. The casting process can form internal cooling channels, threaded inserts, or complex curved surfaces that are impossible or extremely expensive to produce mechanically. This allows you to reduce the number of assembly units. Instead of an assembly of 5 parts connected by welding or bolts, we get one monolithic mechanical part. This increases reliability and reduces the labor intensity of assembly on the customer's assembly line.

However, there are limitations. If the part has simple geometric shapes (cylinder, cube) and large processing allowances, casting may lose out to forging or rolling. Forged blanks have a more directional fiber structure, which is important for shafts subject to torsion. We honestly warn customers: if your part is a simple flange, you do not need a LVM. Our expertise is in saying “no” where technology is ineffective.

Certification and compliance with international standards

To enter the EU and EAEU markets, mechanical parts must comply with a number of directives. The main standard for steel casting in Russia and the CIS countries is GOST 977-88 “Steel castings. General technical conditions." It regulates mechanical properties, chemical composition and control methods. For export contracts, we ensure compliance with the European standard EN 10213 (Technical delivery conditions for steel castings for pressure purposes) and the American ASTM A216/A351.

An important aspect is traceability. Each batch of mechanical parts is accompanied by a quality certificate, which indicates heat numbers, results of chemical analyzes and mechanical tests. If a defect is identified by the consumer, we can pull up archival data and determine exactly on what day and on what furnace the casting was made. This requirement is mandatory for suppliers to the oil and gas sector (API 6D, API 600 standards).

Our production quality management system is certified according to ISO 9001:2015. Regular audits confirm compliance with the procedures for incoming control of raw materials, maintenance of melting logs and calibration of measuring equipment. For special applications (nuclear energy, defense), certification is available according to more stringent industry standards, including the requirements of Rostechnadzor. This level of compliance with international regulations such as PED and ASME is the operating standard for leading market players includingWuxi Kaisheng LLC, whose products are widely used in the energy conservation and chemical industries due to their guaranteed thermal efficiency and reliability in extreme conditions.

Customs clearance also requires correct coding of the Commodity Nomenclature for Foreign Economic Activity. Mechanical parts made of ferrous metals are most often classified in group 73 (Products made of ferrous metals) or 84 (Nuclear reactors, boilers, mechanical equipment), depending on the degree of readiness and functional purpose. An incorrect code can lead to cargo delay at the border and fines. We provide complete technical documentation for the client's customs broker.

Frequently Asked Questions

What is the minimum order quantity for mechanical parts?

Technically, we can produce from 1 piece using 3D wax model printing technology. However, the economically feasible minimum for the traditional LBM process is 50–100 kg of the total weight of the castings per order. This is due to the costs of preparing the ceramic mass and starting the kiln. For development and development work (R&D), we offer a rapid prototyping service with a turnaround time of 10-14 days, where the unit cost will be higher, but the overall development costs will be lower.

Is it possible to weld mechanical parts made from LVM?

Yes, most steels used in investment casting (carbon, low alloy, austenitic stainless) are highly weldable. However, preheating of the part to 150–200°C is required to prevent the formation of cold cracks in the weld area. After welding, a vacation is required to relieve stress. We do not recommend welding parts made of high-carbon steels without special technology, since the risk of destruction is too great.

How long does it take to make a mold and the first batch?

Manufacturing a metal wax injection mold takes 15 to 25 working days depending on the complexity of the geometry. After approval of the wax model sample, the production cycle for the first batch of metal castings is another 20–25 days. Thus, the total time to receive the first finished mechanical parts is 1.5–2 months. To speed up the process, we can use aluminum molds for small batches, reducing the tooling production time to 7 days.

Do you guarantee that there are no internal defects?

We guarantee quality compliance with the results of non-destructive testing (NDT) carried out in accordance with the order specifications. The standard package includes visual and penetrant inspection of 100% of products. Ultrasonic and X-ray inspections are carried out selectively or continuously as required. Statistics show that the level of internal defects in our production does not exceed 0.8%. If hidden defects are discovered within the warranty period, we will cover the costs of product replacement and logistics.

Do you work with customer-supplied raw materials?

Yes, we accept customer-supplied raw materials (metal charge) from customers, especially if specific grades of alloys or recycling of certain categories of scrap are required. However, we are responsible only for the casting process, and not for the chemical composition of the metal provided. Before melting, a rapid analysis of the charge is carried out. If the composition does not meet the requirements, we offer the service of correcting the alloy by adding ligatures for an additional fee.

Practical recommendations for placing an order

To avoid delays and additional approvals, please include a 3D model in STEP or IGES format along with a 2D PDF drawing when submitting a mechanical quote request. Be sure to include basic overall dimensions, critical surface tolerances, and cleanliness requirements on the drawing. If you have preferences on the steel grade, indicate both the Russian GOST and the foreign equivalent (AISI, DIN) to avoid double interpretation.

Pay attention to the packaging. Mechanical parts with complex shapes are sensitive to shock loads during transportation. Мы используем индивидуальную упаковку в гофрокартон с пенопластовыми ложементми и деревянную обрешетку для паллет. Это добавляет около 3–5% к стоимости заказа, но полностью исключает бой керамики (если деталь не обработана) и повреждение геометрии при доставке морем или ж/д транспортом.

При планировании бюджета учитывайте сезонный фактор. В четвертом квартале года загрузка литейных производств максимальна из-за выполнения годовых планов предприятиями. Сроки изготовления могут увеличиться на 1–2 недели. Рекомендуется размещать заказы на крупные партии во втором квартале, когда производственные линии имеют свободные мощности. Это также позволяет провести более тщательную отладку технологического процесса без спешки.

Не забывайте про постобработку. Даже самая качественная отливка требует удаления следов литников. Включите в спецификацию требование к качеству зачистки. Обычно это “зачистка заподлицо с поверхностью” или “зачистка с оставлением припуска”. Первый вариант дороже, но готов к монтажу. Второй вариант дешевле, но требует ваших ресурсов на финишную обработку. Четкое ТЗ на этом этапе сэкономит деньги обеим сторонам.

Conclusion

Механические детали, изготовленные методом литья по выплавляемым моделям, представляют собой оптимальный баланс между сложностью геометрии, механическими свойствами и себестоимостью для средних и крупных серий. Технология позволяет реализовывать инженерные решения, недоступные для других методов формообразования, обеспечивая высокую повторяемость и стабильность характеристик. Ключ к успеху — в партнерстве с производителем, который обладает не только оборудованием, но и глубокой металлургической экспертизой.

Мы понимаем, что каждый проект уникален и требует индивидуального подхода к выбору сплава, конструированию литниковой системы и контролю качества. Наша команда готова провести бесплатный аудит вашей конструкторской документации и предложить оптимизацию для снижения цены без потери надежности. Доверьте производство ответственных узлов профессионалам с многолетним опытом работы на глобальном рынке.

Если вы ищете надежного поставщика для долгосрочного сотрудничества,contact us todayдля обсуждения технических деталей вашего проекта. Мы также приглашаем ознакомиться с нашим каталогом успешных кейсов в разделереализованные проекты литья, где представлены примеры снижения затрат для клиентов из различных отраслей промышленности.