핫 챔버 다이 캐스팅: 중요한 제조 공정에 대한 심층 분석

Hot Chamber Die Casting is a very effective manufacturing process which is used very widely to produce metal parts to very high precision and an excellent finish on the surface. It is particularly suitable for casting metals with low melting points like zinc, magnesium and some alloys containing lead. It is typified by the fact that the injection system is immersed in molten metal, and so, high-speed cycle times and economy of mass manufacturing are possible.

One similar place of comparison always pops up when the castings are considered regarding cold chamber die casting versus hot chamber. Although they are both variations of pressure die casting, they differ so much in terms of design, applications, and compatibility of materials used. An example is the hot chamber die casting, which is high-speed die casting where the furnace has been replaced with a machine. That comes with the limitation of the lower-melting-point metals. Conversely, the cold chamber type of machines is more aptly used with those liquids of a high melting point, such as aluminium and brass, since the hot metal does not come in direct contact with the equipment.

Hot Chamber Die Casting process is characterised by minimal waste of material, low costs of labour, and complex shapes manufacture with high tolerances. It is popular in such industries as automotive, electronics, plumbing and consumer products. Nevertheless, the decision on whether to use cold chamber die casting or hot chamber is also dependent on the type of material used and the part design aspect.

The article examines the important details of 핫 챔버 다이 캐스팅, its parts, materials, process description, constraints, and reasons as to why it is an essential process in the contemporary manufacturing industry.

What is Hot Chamber Die Casting?

Hot Chamber Die Casting is a metal casting technique where the molten metal is injected into a mould cavity at high pressure. The unique part of the given method is where the injection mechanism is placed: It goes directly to the molten metal. Cycle times and production efficiency are high with this setup, especially in metals of low melting point like zinc, magnesium and some lead alloys.

Hot chamber. The name describes the system’s hot chamber as the injection mechanism (a plunger and gooseneck) is in constant contact (filled) with the molten metal area. As the plunger descends, it compresses the molten metal through the gooseneck and into the die cavity. As the metal sets, the mould opens, and the part is ejected, and this process is repeated innumerable times.

Hot Chamber Die Casting Process

Hot Chamber Die Casting Process is a process of high-precision and speed manufacturing technology utilised in the manufacture of metal parts, where the accuracy of the tool is very important, with great surface finishing. It is most appropriate in the alloys of low melting points; zinc, magnesium, and lead are examples of low melting point alloys. Its main characteristics are short cycle times and great material efficiency.

The process is extensive in the manufacturing of a variety of products mainly found in the automotive, electronic, appliance, and hardware industry because of its capability to create complicated ends easily at an affordable per-piece price. The hot chamber die casting process is listed below in a stepwise manner:

Hot Chamber Die Casting Process- Step by Step Overview

1. The Metal is melted

It starts with the molten moulding of the metal (which is usually zinc or magnesium), in an incorporated furnace of the die casting machine. The molten metal is kept at a constant temperature within the metal pot that is directly connected to the casting machine. This unending heat provision ensures that the casting processes are continuous.

2. The process of filling the Injection System

In hot chamber systems, there is a portion of the molten metal with a part of a component known as the gooseneck submerged. The plunger, which runs inside the cylinder of injection, is pulled backwards to a position where the molten metal may gush down to the gooseneck into the inlet hole of injection. The next step will involve injecting this metal into the die cavity.

3. Molten Metal injection

When the gooseneck is filled, the plunger is either pushed forward by hydraulic or pneumatic pressure, which forces the molten metal through the gooseneck channel into the mould cavity (also called the die). This is done at a high rate and pressure to make sure that the cavity is totally filled before the metal begins to harden.

4. Casting and solidifying in the mould

This hot metal in the die is quickly cooled down by the comparatively cold steel of the mould. Solidification takes several seconds, based on the size and complexity of the part. In this step, die cooling channels assist in the removal of heat to ensure that the cycle speed is not reduced and defects such as shrinkage or porosity are avoided.

5. Ejecting and opening of the mould

Once the metal has been solidified, the die halves are opened. The ejector system is placed on the movable half of the mould, and it operates under force via the use of ejector pins and forces the completed casting out of the cavity. It is ensured that the part can come out without being damaged during ejection.

6. Secondary operation and Trimming

After it is ejected, the piece might contain an extra material called flash, runners or sprues. These are either hand-trimmed or auto-trimmed. The part can be processed further depending on the application, like surface finishing, machining or coating.

7. Repeat Cycle

The machine clears and cleans up to be used again. Hot chamber die casting is characterised by having such a quick cycle time, sometimes creating a few finished parts in just 10 to 20seconds according to the complexity and size of the part.

Cycle Time and Efficiency

The speed is the greatest advantage of the process of hot chamber process. Hot chamber machines. Unlike cold chamber die casting, where the metal has to be ladled into the chamber, the metal is pulled out of the furnace. This saves the cycle steps and enhances the production efficiency.

The advantages of This Process

• Shorter cycle times and great productivity
• Real high-dimensional performance and repeatability
• Better surface finish, which in many cases negates the need to perform follow-up processing
• Economy in the use of material, and wastage a minimised
• Friendly to automation, which allows large-scale production at a reasonable price.

Hot Chamber Die Casting Materials

The Hot Chamber Die Casting process is suitable for metals and alloys whose melting points are low to moderate. The materials used should not be able to corrode any steel component (such as the gooseneck and plunger system) as they are continuously wetted with molten metal during the casting process.

The most frequently used materials that are used in Hot Chamber Die Casting and their peculiarities and general application are presented below:

1. Zinc Alloys

The most common material used in the die casting process (hot chamber) is Zinc. It has good castability, strength and surface finish, which makes it very popular in a variety of industries.

Key Benefits:

• Very low melting point (~419 °C or 786 o F )
• Big strength-to-weight ratio
• Splendid flow and high accuracy of dimensions
• Good corrosion-resistant properties
• Low melting temperature, hence long die life

Common Alloys of Zinc, which include:

• Zamak 2, 3, 5, 7 (Zamak 3 is the most popular one)
• ZA alloys (Zinc-Aluminium), but a better metal content of aluminum may be more suitable for the cold chamber.

애플리케이션:

• Automotive parts
• Electrical components
• Constructions and fixings
• Tooth exactness gears and cases

2. Magnesium Alloys

Magnesium is the lightest structural metal, and it has a better strength-to-weight ratio. The reason why it is used in hot chamber die casting is that many of the parts they use here need strength as well as minimal mass.

Key Benefits:

• Lightweight (approximately 33 per cent lighter than aluminum)
• They are well locked and stiff, Good strength and rigidity
• Superb EMI/RFI shielding (suitable for use in electronics)
• Environmentally friendly and recyclable

Common Alloys:

• The most common magnesium alloy used in die casting is AZ91D.

애플리케이션:

• The casings of laptops and smartphones
• Frames of the automotive dashboard
• Aerospace components
• 전동 공구

Note: Although magnesium may also be cast on a cold chamber machine, it is preferable to use hot chamber machines when the magnesium being cast is small. This is because cycle times are shorter.

3. Lead and tin Alloys

Lead and Tin alloys have mostly been eliminated because of health and environmental restrictions in hot chamber die casting, but were used in special applications in the past.

Key Benefits:

• Low melting points (~327 o C (lead) and ~232 °C (tin))
• High density (best suited to uses such as balance weights, or radiation shields)
• Superb dimensional stability

애플리케이션:

• Antique-style fittings
• Precision instruments
• Ammunition components
• Decorative items

Warning: Because of its toxicity, lead-based alloys are today severely limited in many industries and countries.

4. Cadmium-based Alloys (Not so Com)

These have been infrequently applied to toxicity and regulatory reasons, but had previously been selected because of service which is excellent casting service, as well as wear resistance.

The reason why High-Temperature Alloys are not used.

A characteristic limitation of the Hot Chamber Die Casting such as:

• 알루미늄
• Brass
• 구리
• Steel

The hot chamber machine would be damaged or corroded as this type of metal would have a high temperature and reactivity to the submerged parts of the hot chamber machine, eg the plunger and the gooseneck, etc. These are rather found in use in Cold Chamber Die Casting, which isolates molten metal and the injection mechanism. 

Summary Table: Suitable Materials In Hot Chamber Die Casting

Reasons Why Aluminum Alloys Are not Applicable in Hot Chamber Die Casting?

Though aluminum alloys have so many applications in the die casting industry, because of their strength, lightweight property and corrosion resistance, they cannot be hot cast in the hot chamber die casting. Rather, they are normally treated by the cold chamber die casting technique.

To explain this, what are the technical and material reasons that the “aluminium alloys are not used in hot chamber die casting”

1. Large melting temperature

The major factor which makes aluminum not compatible with the hot chamber process is that it has a high melting point. The majority of the aluminum alloys will melt around 660 o C (1220 o F) and above.

The gooseneck and plunger, as well as other injection parts, are always immersed in molten metal in hot chamber machines. It is effective in the case of relatively low-melting-point metals such as zinc (419 o C), magnesium (~650 o C). These components would, however, be quickly degraded or destroyed at the higher temperatures of aluminum and result in the failure of the equipment and costly repairs.

• Cold Chamber compatible SAC suit
• Hot Chamber too hot to say the least

2. Attack on Steel Parts

Aluminium is chemically reactive and tends to corrode ferrous metals, particularly, high temperatures. Under hot chamber systems in which items such as the gooseneck and the nozzle are in the molten pool, aluminium would not only corrode but would also eat through the steel parts would dramatically shortening the life cycle of the machine.

This response not only reduces the life of the equipment but also contaminates the molten metal and causes poor casting and imperfections in the final product.

3. Problems of compatibility of equipment

Hot chamber machines are small, fast machines, but suitable to perform quick repetitive castings of low melting point metals. The built-in furnace is closely interlinked with the injection system. To use alloys with a high melting point, such as aluminium, would require:

• Reinforced components
• High-temperature-resistant alloys are made of special alloys
• More complicated insulation systems

These would render the simplicity and the speed benefit of hot chamber die casting ineffective. This is the reason why assemblers choose to use cold chamber machines in which they pour the molten aluminum outside, and the injection system is also not submerged.

4. Oxidation and Dross Risk

At high temperatures, aluminum is prone to oxidation easily in the presence of air. This oxidation may cause the dross (aluminum oxide) to form in a hot chamber arrangement where the metal is continuously exposed:

• It pollutes the metal
• Surface defects are caused by causes
• And results in mechanical deficiencies of the finished product

This risk is minimized by the fact that cold chamber die casting reduces the amount of time molten aluminum is exposed.

5. Safety Concerns

Processing aluminum in a hot chamber machine would pose a great risk of burn injuries, leakage and breakdown of the machine. Further thermal stress associated with working at higher temperatures exposes to further threat of:

• There is bleeding molten metal leakage
• Blowing out reactions of steam
• Pressure components failure

The cold chamber systems enable improved isolation and safety regulation with these high temperatures.

Comparison between Hot Chamber and cold Chamber on Aluminum

Systems of Hot Chamber Die Casting Components

The Hot Chamber Die Casting process is based on a group of well-engineered components that complement each other to produce accurate and repeatable castings. All the parts are very vital when it comes to efficiency, speed, and accuracy. Being aware of these elements contributes to the production, preventive, and quality controls.

The main constituents of a Hot Chamber Die Casting machine are as shown below:

1. One more Furnace (Metal Pot)

In the core of the system, there is a furnace, or the so-called metal pot, where the molten metal, which will be used in casting, is situated. In hot chamber die casting, an equivalent furnace is incorporated into the machine and maintains the metal at a sufficiently high temperature to use it immediately. As opposed to cold chamber systems, the process of immersion of other components in this molten bath separates it.

2. Gooseneck

Gooseneck constitutes a bent metal pipe connecting the furnace with the injection chamber. It is crucial in redirecting hot metal from the pot to the mould. The gooseneck will be composed of strong, heatproof materials because it is constantly in contact with molten metal. The design further assists in sustaining the pressure and makes the metal buttery in injection.

3. Plunger/Injection Cylinder

The plunger mechanism or injection cylinder does the task of forcing molten metal into the die cavity. It operates with the gooseneck. When the plunger is pushed down, the molten metal becomes pressurised, causing the melt to force its way through the gooseneck into the mould. This should be done in a fast and forceful manner so that the die cavity will be filled fully.

4. Die/Mould Assembly

The die or mould is manufactured as two sections, the cover die (which is stationary) and the ejector die (movable). To get the final product, these well-machined halves will make up the cavity. The mould is frequently water cooled and contains vents and gates, and runners to maintain a desirable flow and cooling effect. To eliminate the solidified part, there are pins at the ejector side following casting.

5. Clamping Unit

The clamping unit ensures that the die halves are well bonded together during the injection of molten metal. It has to resist the casting pressure that arises when casting. When the metal cooled and solidified, the clamping unit opens the mould, and the finished part comes out of it. The clamping should also be strong in order to avoid metal leakages and to maintain the quality of parts.

6. Ejector System

Once the part solidifies, the ejector system is used. A part is ejected out of a mould cavity by ejector pins, which are usually found in the moving half of the die. This system has to be well coordinated such that the final product is not affected and the mould is not damaged.

7. Cooling System

Cooling is vital in order to control the cycle times and avoid defects. The circulating cooling system makes use of water or oil channels in the die in such a manner that the circulating fluid cools the metal in a short period as well as in a fast and uniform manner. A faster cooling also prolongs the life of the mould, and enables the parts to be handled at an increased rate.

8. Lubrication System

Between cycles, die casting moulds are lubricated to avoid sticking and wear. Lubricants are sprayed on the die to help in releasing the parts as well as ensure a long life of the tools and stability of casting conditions. There is usually automated application to facilitate the even and timed application.

9. Control Panel

Hot chamber die casting systems are also available in the modern system and are fitted with a digital control panel enabling management of temperature, injection speed, cycle time, and clamping force, among others. Such systems enhance uniformity in the processes, reduce the level of human error and ease the setting of parameters to suit various part designs.

10. Safety Features

Safety features have been incorporated in the machine because of the temperature and pressure when it is hot. They comprise shut-offs, shields, interlocks and temperature monitors to safeguard the operators as well as the equipment.

The Benefits of Hot Chamber Die Casting

The Hot Chamber Die Casting process has many advantages, such that many manufacturers are always willing to engage in the process:

1. High-Speed Production

The injection system forms part of the molten metal reservoir system, and so metal does not have to be ladled into the chamber. The combination of this system yields higher injection speeds and low cycle time- hot chambers systems are therefore suitable in homes mass production.

2. Economy of Materials

Very little wastes are generated through this process. The leftover material can be used again most of the time, and thereby the total cost of the material reduces considerably. This aspect of sustainability is an increasing problem in contemporary production.

3. Better Surface finish

Surface finishes of parts manufactured by the hot chamber casting are usually of good quality. In many cases, this saves on extra machining or finishing operations.

4. Long Mould life

As the metals used in the process of Hot Chamber Die Casting have lower melting points, those metals are less aggressive on moulded materials. This causes increased diesel life and lower maintenance charges.

Shortcomings of Hot Chamber Die Casting

One cannot argue with the fact that “Hot Chamber Die Casting” is not without limitations:

Material Limitations: It does not go well with the metals that have high melting temperatures, such as aluminium and copper. The internal components of the machine can be harmed by either corrosive or heating effects of these.

Equipment Wear: The equipment wear can be a factor, even though less severe than the cold chamber casting, whereby the apparatus is constantly exposed to melted metal.

Size Limitation: It can be applied to smaller and medium components since further expansion of the system can be inefficient and complicated.

핫 챔버 다이 캐스팅 애플리케이션

This is a widely applied technique in all sorts of industries, particularly where precision and large-scale parts are required:

• 자동차: Pieces such as carburettor houses, fuel system units and transmission components.
• Consumer Electronics: Portable cases, multi-functional parts of devices and equipment.
• Hardware and Tools: Hardware material based on Zinc, hinges, handles, locks, etc.
• Medical devices: Miniature, highly precise and tough devices.

The hot chamber process is fast and consistent, which is a quality that is advantageous to these industries. With most of these products being models that need detailed designs, the dimensional stability that is given by the Hot Chamber Die Casting comes as a big plus.

Cold Chamber Die Casting vs Hot Chamber: Get to grasp the difference

In the comparison between cold chamber die casting and hot chamber, there are various aspects which will need to be put into consideration, such as the compatibility of the materials, rates of production, cycle and the design of the equipment.

1. Material Use

The type of metal is also one of the most significant differences between cold chamber die casting vs hot chamber. Hot chamber process only takes on metals which have low melting points, and cold chamber process takes on aluminium, brass and copper alloys which have high melting points.

2. Injection System

The injection mechanism in the hot chamber method is immersed in molten metal. Cold chamber casting, on the other hand, involves ladle feeding molten metal to the shot chamber by hand and injecting it into the die. This further action delays the process.

3. The cycle time and efficiency 

Cycle time and efficiency denote the time it takes to turn over the sample or input of data in a cycle. There is also a big difference between cold chamber die casting vs hot chamber, with regards to cycle time. Hot chamber process is quick and hence suitable for large volume runs. Although cold chamber casting is slower, it can be eased with more aggressive metals and hotter temperatures.

4. The Size and the Complexity of Components

Sections or parts that are larger or need materials that are more permanent are usually cast using the cold chamber method. Comparatively, the hot chamber casting is suitable for smaller and complex parts where a cycle speed is vital.

When choosing a decision between hot chamber and cold chamber die casting, the manufacturer will have to look at the tradeoffs in the speed and material properties and wear on the equipment.

Design considerations in Hot Chamber Die casting

To design a part suitable for a hot chamber die casting part, the following issues need to be looked after: mould flow, parting lines, wall thickness, and ejector location. Since the molten metal is injected at high levels, the venting and cooling system plays an important role in preventing defects such as entrapment of air, shrinkage or incomplete fills.

The tolerances of the Hot Chamber Die Casting Process are usually smaller than those required by all the other casting processes, hence the reason why it is always used in manufacturing parts that need precision and have little machining.

Environmental and Economic Effects

Sustainable manufacturing is drawing more and more attention from modern foundries. Hot Chamber Die Casting is ideal in achieving this objective in that it shows a low scrap level and energy savings. The total carbon footprint of a part is much less than in other methods to produce metal parts because the metal being processed is recycled (no new metal is extracted), and cycle times are short.

The process is more economical when it involves a large output. Its cost of setting up the first die and machine may be high, but as the unit production scale increases, the costs involved drop tremendously.

결론

Hot Chamber Die Casting has a very critical place in the industries that require speed, accuracy, and efficiency in their production. Knowing of its operation and in making the comparison of cold chamber die casting and hot chamber connections, an engineer will be able to make informed decisions on the choice of the most suitable process in line with the needs of their product.

Whether to use one or the other, the metal nature, the needed production volume, and the final usage should be taken into consideration. Hot chamber casting is unrivalled in efficiency and quality with respect to making small to medium components of low-melting-point metals.

All in all, despite the existence of the two methods of casting, Hot Chamber Die Casting will always be the first solution to the problem of manufacturing quality components in time and dependably. With the manufacturing process becoming more efficient and sustainable, the need for such optimised and sustainable processes, such as the hot chamber casting, will only increase, which makes this method more applicable than ever before.

자주 묻는 질문

1. How does cold chamber die casting and hot chamber main casting?

The injection system is the chief difference. The injection mechanism in hot chamber die casting is immersed in molten metal. The temperature is greater in the cold chamber, and the metal is ladled outside.

2. What are the most suitable metals for Hot Chamber Die Casting?

The metals that are commonly used are zinc and magnesium alloy since they have low melting temperatures, and they suit the immersed injection system in which they are used to make.

3. Aluminium is not applicable in Hot Chamber Die Casting, why?

Aluminium is known to have a high melting point and is corrosive to the steel parts in the machine. The cold chamber method is used in its processing to prevent damage to its equipment.

4. What are the Hot Chamber Die Casting benefits?

It provides short cycle times, low labour costs, small tolerances, and high surface finishes of small and medium-sized parts.

5. Is Hot Chamber Die Casting appropriate for large components?

Generally, no. It is minimized when the parts are small and detailed. Too large dimensions usually mean a need for cold chamber die casting because of the size and material restraint.