Weighing equipment: lost wax casting - inexpensive 

Weighing equipment: lost wax casting - real numbers and hidden risks

The dosing accuracy in weighing equipment directly depends on the geometry of the housing and the stability of the internal channels, which cannot be obtained using traditional sand molding.Weighing equipment: lost wax casting - inexpensivebecomes an affordable solution only if you understand the technological nuances of the process, and not just search for the lowest price per kilogram of metal. In our practice, we encountered a situation where a batch of strain gauges failed after three months of operation due to microcracks in the housing caused by uneven cooling of the mold - this cost the client 15% of returns and reputational losses in the CIS market.

Lost wax casting (IMC) for weighing technology components is not just a way to achieve complex shapes, it is the only method that guarantees the absence of seams and minimal shrinkage in critical areas where sensitive elements are attached. When you see an "inexpensive" offer, ask the question: what grade of steel is used? Is the heat treatment regime followed after casting? And most importantly, does the supplier have a GOST or ISO certificate of conformity for this batch? The answers to these questions separate a reliable partner from an intermediary who sells marriage under the guise of savings.

We analyzed more than 40 production runs over the past year and found a clear correlation between the cost of surface treatment and the life of the weighing unit. Cheap casting often requires subsequent mechanical rework, which compromises the integrity of the surface layer and reduces corrosion resistance. In this article, we will look at how to choose a supplier who will offer the best price-quality ratio, based on actual roughness parameters, alloy chemistry and geometric tolerance control.

Why LVM is critical for precision weighing assemblies

Traditional casting methods leave mold release marks, which become stress raisers in weighing equipment. Under dynamic loads, typical of conveyor scales or dispensers, it is in these areas that fatigue cracks originate. The technology of lost wax models allows you to create monolithic structures of any complexity without joint lines. This is especially important for strain gauge housings, where even a micron deviation in the mounting plane can lead to measurement errors in excess of 0.05%.

In our workshop, we carried out comparative tests of two batches of housings: one was made using sand-clay molding, the other was made using lost wax models from steel 20X13. After 50,000 loading cycles, the LVM samples showed a change in geometry of less than 0.002 mm, while the sand casting deformed by 0.015 mm. For high-precision laboratory balances, such a difference is unacceptable. Moreover, the internal structure of the metal with LVM is more homogeneous, which ensures stability of readings at temperature fluctuations from -40°C to +60°C.

Another critical aspect is the ability to integrate fasteners directly into the casting. Instead of drilling holes after the fact, which weakens the section of the part, we form them in a wax model. This eliminates the risk of chips getting inside the housing and damaging the strain gauges. Customers who switched to this design noted a reduction in the percentage of defects during assembly by 18%. If your current supplier only offers simple post-casting treatment, you are losing out on the reliability of the final product.

The cost of equipment for LVM is higher than for sand casting, but with mass production of 500 pieces or more, the price per unit of production is equalized. Savings are achieved by reducing machining: the machining allowance is only 0.3–0.5 mm versus 2–3 mm for traditional methods. This means less tool, energy and machine time consumption. Calculation of the payback shows that already on the third batch you are at a profit compared to cheap but labor-intensive casting.

Key parameters for choosing a casting supplier for weighing equipment

When evaluating a commercial proposal, the first thing you need to look at is not the price per ton, but the chemical composition warranty. For weighing equipment, we recommend using stainless steel grades 12Х18Н10Т (AISI 321) or 20Х13 (AISI 420). Suppliers who work “inexpensively” often replace them with cheaper analogues with a higher content of sulfur and phosphorus, which sharply reduces impact strength. Request a spectral analysis protocol for each heat - this is your right according to GOST 7565.

The second parameter is the casting accuracy class. For critical components of weighing equipment, an accuracy class of at least CT4 according to ISO 8062-3 is required. Many Chinese and some Russian factories offer CT6 or CT7, citing lower prices. However, such tolerances require significant subsequent machining, which offsets the initial savings. In our practice, there was a case when a batch of housings with IT14 approval instead of the required IT9 led to the fact that 30% of the products had to be sent for re-melting due to the inability to ensure the alignment of the holes.

The third criterion is the presence of our own non-destructive testing (NDT) laboratory. Penetrant testing (color flaw detection) is mandatory for each casting intended to operate under load. Ultrasonic testing is recommended for large parts weighing over 5 kg. If a supplier says they perform random inspections “at the request of the customer,” this is a red flag. Hidden pores and cavities may only appear after six months of use, when the warranty has already expired.

The fourth point is certification of the quality management system. Having an ISO 9001 certificate is a basic requirement, but to enter the EAEU markets, you also need a certificate of compliance with the technical regulations of the Customs Union (CU TR). The absence of EAC marking on products makes them illegal for sale in Russia, Belarus and Kazakhstan. Check the authenticity of certificates in the RosAccreditation register - forgeries are more common than you might think.

Comparison of technologies: LVM versus sand casting and rolled metal processing

The choice of technology for producing housings for weighing equipment often comes down to a dilemma: save money at the start or reduce operating costs. Below is a detailed comparison of the three main approaches, based on our experience delivering more than 10,000 units last year.

As can be seen from the table, processing from a single piece of metal gives the best accuracy, but the cost of such a part is 3-4 times higher than a cast part. This option is justified only for prototypes or ultra-precise analytical balances with low load capacity. Sand casting is attractive because of its low tooling costs, but the machining costs and high scrap rate during finishing make it unprofitable for production runs of more than 200 pieces.

LVM occupies the golden mean. It allows you to produce parts that are close in shape to the finished product (near-net-shape), minimizing metal waste. This is especially beneficial when using expensive stainless alloys. For example, when producing a weighing terminal housing from 12Х18Н10Т steel, metal savings amount to up to 4 kg per part compared to milling. In terms of an annual program of 5,000 units, this is hundreds of thousands of rubles in direct savings.

However, LVM has a limitation: the maximum weight of a single casting usually does not exceed 50-70 kg due to the technological features of the process. For heavy platform scales, this method may not be applicable, and here you will have to return to sand casting or welded structures. But for most components of dosing and filling equipment, the weight range from 50 g to 20 kg is ideally covered by the lost wax technology.

Economic model: how to get an “inexpensive” price without losing quality

The phrase "inexpensive" in the context of industrial casting is often misleading. The real savings come not from a low price per kilogram of casting, but from a reduction in the total cost of ownership of the product. We have developed an algorithm that allows our clients to optimize their purchasing budget by 20-25% without compromising on quality.

The first step is to unify the design. If you order 10 different body styles in small quantities, the cost of tooling is spread over a small number of units, driving up the price. Ask our engineering department to audit your design documentation. It is often possible to combine 3-4 parts into one universal platform with minor modifications. This increases the lot size for each tool and reduces the unit cost.

The second step is choosing the optimal alloy. AISI 316L steel is not always required. For many applications in dry rooms, AISI 304 steel or even 40X structural steel followed by nickel plating is sufficient. The difference in the price of raw materials can reach 40%. Our technologists will help you select a material that will provide the necessary service life under your operating conditions, without overpaying for excess characteristics.

The third factor is logistics and packaging. Weighing equipment is fragile and damage during transportation is a common problem. We use individual cell packaging made of foamed polyethylene, which eliminates damage. Although this adds 3% to the cost, it is cheaper than returning a defective batch and downtime to the customer's production. In addition, consolidation of cargo and shipping by containers directly from the plant allows you to avoid intermediary markups at ports.

It is important to take into account currency risks. When working with international suppliers, fix the exchange rate in the contract or use calculations in yuan/rubles, bypassing the dollar. Over the past year, the volatility of currency pairs led to a change in the final price by 15% for those who did not hedge risks. We offer price fixation in rubles for the entire duration of the supply agreement, which gives you financial certainty.

Typical mistakes when ordering castings and how to avoid them

One of the most common mistakes is the lack of technical specifications (TOR) with clearly defined requirements for non-destructive testing. Customers often write simply “no defects,” which is interpreted differently by the supplier. For one it is the absence of through cracks, for another it is the absence of any imperfections visible to the eye. As a result, you receive a batch that formally complies with the contract, but is unsuitable for assembling precision components. Always indicate a specific control standard, for example, GOST 18442 for the capillary method.

The second mistake is ignoring material shrinkage. Different grades of steel have different linear shrinkage coefficients (from 1.8% to 2.2%). If the tooling manufacturer does not take this into account accurately, the finished parts will not be assembled into an assembly. We have seen cases where the mounting holes were misaligned by 0.5mm, making assembly impossible without reaming, compromising the corrosion protection. Require a wax model drawing to be submitted for approval before going into production.

The third problem is the wrong choice of method for cleaning castings. Shot blasting must be carried out with shot of a certain size and hardness. Using too aggressive shot can create hardening of the surface or, conversely, knock out metal in thin sections. For weighing equipment with thin case walls, we recommend using glass beads or fine electrocorundum. This maintains geometry and ensures uniform roughness.

The fourth mistake is saving on heat treatment. After solidification, the casting has internal stresses, which eventually lead to warping. Annealing or hardening and tempering are required to relieve these stresses. Some suppliers skip this step to speed up shipment. This cannot be determined visually, but after six months of use the weights will begin to “float”. Insist on providing a heat treatment temperature chart for each batch.

Certification and compliance with standards for the markets of the Russian Federation and the EAEU

Entering the weighing equipment market is impossible without compliance with regulatory requirements. The main document is the Technical Regulations of the Customs Union TR CU 010/2011 “On the safety of machinery and equipment”. For scales, compliance with metrological requirements regulated by Federal Law No. 102-FZ “On Ensuring the Uniformity of Measurements” is critically important.

Products subject to mandatory certification must have the EAC circulation mark. The procedure includes analysis of the state of production, testing of samples in an accredited laboratory and inspection control. Our plant undergoes annual audits, which is confirmed by valid certificates. When ordering a batch, make sure that the accompanying documents indicate the number of the certificate of conformity and the authority that issued it. You can check the validity of the document in the unified register of certificates of the Russian Accreditation Agency.

For export to non-CIS countries, certification according to OIML (International Organization of Legal Metrology) standards may be required. Our products are tested according to OIML R60 guidelines for strain gauges. This opens up access to markets in Europe and Asia. Documentation is generated in Russian and English, which simplifies customs clearance.

Environmental safety is also an important aspect. The production of fiber materials involves the use of binders and solvents. Our plant is equipped with modern emission treatment systems, which allows us to comply with MPC standards. This is confirmed by the enterprise’s environmental passport. For large industrial customers, the presence of such a passport is a mandatory condition for the supplier’s admission to the supply chain.

Experience of global manufacturers: synergy of technologies and materials

The choice of a reliable partner is often determined by its experience in working with complex alloys and high quality standards. A prime example of a company demonstrating the highest level of competence in working with exotic and corrosion-resistant materials isWuxi Kaisheng Electric Power and Petrochemical Equipment Co., Ltd.. Although this company's core focus is on the design and manufacture of heat transfer equipment for the oil, gas and energy industries, their technological background directly intersects with the requirements for precision castings for weighing equipment.

Wuxi Kaisheng's specialists have unique experience with titanium alloys, high-pressure ASME structures and complex compositions such as N06625 nickel alloys, C70600 copper-nickel alloys and C46400 marine brass. Their products, including 316 stainless steel corrugated tube bundles and 321 steel tubesheets, are certified to the strictest international PED and ASME standards. This experience ensures an understanding of the critical importance of zero defects, high corrosion resistance and resistance to extreme temperatures and pressures - qualities that are absolutely necessary for critical components of weighing equipment operating in aggressive environments.

The use of similar production facilities and engineering approaches allows us to adapt advanced petrochemical solutions to weight engineering problems. For example, quality control technologies used in the manufacture of waste heat boilers and air coolers can be successfully transferred to the production of strain gauge housings, providing the same reliability discussed above. Collaboration with partners at the level of Wuxi Kaisheng provides access to materials and processing technologies that are rarely available on the mass market, allowing the creation of next-generation weighing equipment with unprecedented service life.

Cases of implementation: from laboratory scales to industrial platforms

Let's look at a real example of modernizing a production line for truck scales. The customer used welded sheet metal housings. The problem was poor tightness and the need for additional painting of each seam. The annual cost of anti-corrosion protection was about 2 million rubles. The transition to monolithic LVM housings made of 09G2S steel made it possible to completely eliminate welds. Sealing has increased to IP68 without additional seals. The service life of the coating has increased from 3 to 7 years. Total costs decreased by 35% based on a 5-year operating cycle.

Another case concerns the production of medical scales. The requirements for a clean surface and the absence of places where bacteria accumulate dictate the use of polished stainless steel. Фрезеровка таких корпусов была крайне дорогой из-за вязкости материала и сложности внутренней геометрии. Внедрение ЛВМ с последующей электрохимической полировкой позволило получить поверхность Ra 0.4 мкм сразу после литья с минимальной доводкой. Время цикла производства сократилось с 14 до 5 дней, а себестоимость упала на 40%. Это позволило заказчику снизить розничную цену продукта и увеличить долю рынка.

В сегменте железнодорожных весов мы столкнулись с задачей повышения вибростойкости. Традиционные чугунные корпуса давали трещины при прохождении составов. Замена материала на высокопрочную сталь 35ХГЛ и применение технологии ЛВМ для создания ребер жесткости сложной формы решило проблему. Ресурс изделия увеличился с 2 до 5 лет интенсивной эксплуатации. Клиент отметил отсутствие рекламаций по данной позиции за последние два года, хотя ранее они поступали ежемесячно.

Эти примеры показывают, что технология ЛВМ применима в самых разных сегментах весостроения. Ключ к успеху — правильный инжиниринг детали на этапе проектирования. Не пытайтесь просто скопировать деталь, сделанную под другую технологию. Adapt the design to the casting capabilities: add radii in the corners, optimize wall thickness, provide a gating system. Наши конструкторы готовы провести бесплатный аудит ваших чертежей и предложить оптимизацию под ЛВМ.

План действий: как начать сотрудничество и получить образец

Если вы заинтересованы во внедрении компонентов, изготовленных по технологии литья по выплавляемым моделям, мы предлагаем прозрачный алгоритм входа в проект. Первый шаг — заполнение опросного листа, где вы указываете требуемый материал, тираж и основные размеры детали. На основании этих данных наши технологи рассчитывают предварительную стоимость и сроки изготовления пресс-формы.

Затем мы подписываем соглашение о неразглашении (NDA) и приступаем к 3D-моделированию литниковой системы. Вы получаете визуализацию будущей отливки и отчет о прогнозируемых усадках. Только после вашего утверждения начинается изготовление опытной партии. Обычно это занимает 20-25 рабочих дней. Образцы проходят полный цикл испытаний в нашей лаборатории, и вы получаете протоколы тестов вместе с деталями.

При положительном результате испытаний заключается долгосрочный контракт с фиксацией цены и объемов. Мы гарантируем приоритетное производство для постоянных партнеров и возможность хранения страхового запаса на нашем складе. Это позволяет вам работать по системе Just-In-Time, не замораживая оборотные средства в запасах.

Не откладывайте модернизацию производства. Конкуренты уже используют преимущества ЛВМ для снижения издержек и повышения качества. Contact us today to receive a custom quote for your project. Мы готовы обсудить условия оплаты, включая отсрочку платежа для проверенных клиентов, и организовать визит на производство для демонстрации технологических возможностей.

Remember:весовое оборудование: литьё по выплавляемым моделям – недорого— это не маркетинговый лозунг, а результат грамотного инженерного подхода и оптимизации процессов. Доверьте производство ответственных узлов профессионалам с опытом и собственной лабораторией.Запросить коммерческое предложениеможно прямо сейчас, заполнив форму на сайте или позвонив по указанному телефону. Your reliability is our reputation.