Sunday, March 2, 2008
Thursday, February 28, 2008
Manufacturing of Die Cast Trucks
The Manufacturing of Die-Cast Trucks
Despite their specialized purpose, die-cast trucks are designed and manufactured in much the same way as die-cast components used for industrial and home applications. From die design through the die-casting and finishing processes, die-cast trucks follow a straightforward path on the road to retail sale.
Designing Die-Cast Trucks for Manufacturability
The first step in the manufacturing process is to design the die for the truck parts. Each part has to be designed for manufacturability so that each part can be properly cast, removed from the die, and has the proper strength to maintain its shape when assembled and handled. Next, a metal alloy must be chosen for the truck parts. Zinc alloys are commonly used because parts can be made with close tolerances with minimal shrinkage after the metal has cooled. Zinc is often alloyed with aluminum to improve the metal’s strength and hardness. Zinc alloys can handle the hot chamber process, resulting in faster manufacturing and cooling times.
The Hot Chamber Die-Casting Process
The die-casting process begins by assembling the die. The die may have multiple cavities for multiples of the same part, or one die may contain different cavities for different parts. The die is assembled with inserts as required and the sprue pin is inserted in the sprue hole in the die. The die is then clamped together to minimize the amount of flash that extrudes out of the seams of the die.
The injection mechanism of the hot-chamber casting machine sits in the molten metal of a holding furnace. The furnace is attached to the die assembly by a gooseneck. The injection cylinder plunger is pulled up, and a port in the injection cylinder opens, allowing molten metal to enter the cylinder. When it is time to cast the part, the plunger is pushed downward, forcing molten metal through the gooseneck and nozzle into the die cavity. The metal flows through the nozzle, around the sprue pin, through the runners and gates into the die cavities. A die may have an overflow cavity to ensure that the main cavities fill completely. The die-cast part is then allowed to cool in the die. The die may also contain a waterline to speed up the cooling process. After the metal has solidified in the die cavity, the plunger is pulled back, and the die can be opened and the casting can be ejected.
Die-Cast Part Finishing
After a die-cast part has been removed from the die, it needs to be finished before it can be assembled into the final product. First, any excess material, such as flash or sprue, is removed from the part. The die-casting process generally produces a good surface finish, so not much post-casting machining is required. After the excess material has been removed and the seams cleaned up, the part can be plated or painted, depending on the function of the part. At this point, the part can be included in the assembly of the truck.
Sources
Engineering Fundamentals - http://www.efunda.com
North American Die Casting Association web site - http://www.diecasting.org/
Despite their specialized purpose, die-cast trucks are designed and manufactured in much the same way as die-cast components used for industrial and home applications. From die design through the die-casting and finishing processes, die-cast trucks follow a straightforward path on the road to retail sale.
Designing Die-Cast Trucks for Manufacturability
The first step in the manufacturing process is to design the die for the truck parts. Each part has to be designed for manufacturability so that each part can be properly cast, removed from the die, and has the proper strength to maintain its shape when assembled and handled. Next, a metal alloy must be chosen for the truck parts. Zinc alloys are commonly used because parts can be made with close tolerances with minimal shrinkage after the metal has cooled. Zinc is often alloyed with aluminum to improve the metal’s strength and hardness. Zinc alloys can handle the hot chamber process, resulting in faster manufacturing and cooling times.
The Hot Chamber Die-Casting Process
The die-casting process begins by assembling the die. The die may have multiple cavities for multiples of the same part, or one die may contain different cavities for different parts. The die is assembled with inserts as required and the sprue pin is inserted in the sprue hole in the die. The die is then clamped together to minimize the amount of flash that extrudes out of the seams of the die.
The injection mechanism of the hot-chamber casting machine sits in the molten metal of a holding furnace. The furnace is attached to the die assembly by a gooseneck. The injection cylinder plunger is pulled up, and a port in the injection cylinder opens, allowing molten metal to enter the cylinder. When it is time to cast the part, the plunger is pushed downward, forcing molten metal through the gooseneck and nozzle into the die cavity. The metal flows through the nozzle, around the sprue pin, through the runners and gates into the die cavities. A die may have an overflow cavity to ensure that the main cavities fill completely. The die-cast part is then allowed to cool in the die. The die may also contain a waterline to speed up the cooling process. After the metal has solidified in the die cavity, the plunger is pulled back, and the die can be opened and the casting can be ejected.
Die-Cast Part Finishing
After a die-cast part has been removed from the die, it needs to be finished before it can be assembled into the final product. First, any excess material, such as flash or sprue, is removed from the part. The die-casting process generally produces a good surface finish, so not much post-casting machining is required. After the excess material has been removed and the seams cleaned up, the part can be plated or painted, depending on the function of the part. At this point, the part can be included in the assembly of the truck.
Sources
Engineering Fundamentals - http://www.efunda.com
North American Die Casting Association web site - http://www.diecasting.org/
Collecting Toy Trucks
An Introduction to Collecting Die-Cast Trucks
Collecting die-cast trucks is a fun and fascinating hobby. Whether you are interested in casual collecting or if you’re a die-hard collector, there is something in this hobby for everyone. When starting out collecting, or if you are purchasing a truck for a collector, there is some basic information that all collectors should know about die-cast trucks.
Die-Cast Truck Types
While some people collect strictly one type of die-cast vehicle, there are a wide range of vehicle types available. Some collectors focus on antique trucks, and others like to collect trucks from a single manufacturer. Others may focus strictly on a type of truck, such as 18-wheelers, and others may have an interest in farm vehicles or construction equipment. It’s important to decide what sort of truck you are most interested in, so you can focus your research and purchasing.
Die-Cast Truck Manufacturers
There are many different manufacturers of die-cast trucks. Some of these manufacturers include:
· Norscott – Norscott is the primary manufacturer of Caterpillar die-cast construction equipment, as well as other brands such as Peterbilt, Kenworth, Case, Claas, Bell, Liebherr and Yale/Hyster.
· Ertl – Ertl is one of the oldest die-cast truck manufacturers. Ertl’s primary focus is on farm equipment, and manufactures John Deere and Case/New Holland farm vehicles.
· Tonkin – Tonkin focuses on road trucks, primarily 18-wheelers, but their collection also includes log trucks and dump trucks.
· New Ray – New Ray Trucks also focus on road trucks, including 18-wheelers and pickup trucks, but their collection also includes specialty trucks such as garbage trucks and tanker trucks.
· Yatming – Yatming is a Hong Kong company that manufactures a wide line of fire trucks and police vehicles, in addition to its automobile lines.
· Corgi – Corgi is a British manufacturer that specializes in branded trucks and limited edition collectable vehicles.
· Tonka – Tonka trucks were manufactured more strictly as toys than many die-cast trucks made today. Tonka is currently owned by Hasbro, and now licenses the Tonka name to Maisto for die-cast vehicles. Today’s Tonka trucks include pickup trucks, farm tractors, big rigs and branded trucks.
Die-Cast Truck Scales
A scale refers to the ratio of the size of the model truck to the size of the actual truck. The primary scales for die-cast vehicles are 1:18, 1:24, 1:43, and 1:64. In a 1:18 scale truck, one inch on the die-cast truck translates to 18 inches on the actual truck. Some collectors prefer one scale of die-cast toy trucks, while other's collect trucks from a variety of scales.
Resources for Die-Cast Truck Collectors
The majority of resources for die-cast truck collectors are web sites created by die-cast truck manufacturers and sites developed by other collectors. While manufacturer web sites can easily be found with a simple search, it is more difficult to locate non-manufacturer resources. The following is a list of web sites for collectors by collectors:
· Uncle Chester’s Toy Trucks - http://unclechesterstoytrucks.com/
· S&K Toy Trucks - http://www.sktoytrucks.com/
· Diecast.Plus.com - http://www.diecast.plus.com/
· Spot-On - http://spot-on-collector.com/
Collecting die-cast trucks is a fun and fascinating hobby. Whether you are interested in casual collecting or if you’re a die-hard collector, there is something in this hobby for everyone. When starting out collecting, or if you are purchasing a truck for a collector, there is some basic information that all collectors should know about die-cast trucks.
Die-Cast Truck Types
While some people collect strictly one type of die-cast vehicle, there are a wide range of vehicle types available. Some collectors focus on antique trucks, and others like to collect trucks from a single manufacturer. Others may focus strictly on a type of truck, such as 18-wheelers, and others may have an interest in farm vehicles or construction equipment. It’s important to decide what sort of truck you are most interested in, so you can focus your research and purchasing.
Die-Cast Truck Manufacturers
There are many different manufacturers of die-cast trucks. Some of these manufacturers include:
· Norscott – Norscott is the primary manufacturer of Caterpillar die-cast construction equipment, as well as other brands such as Peterbilt, Kenworth, Case, Claas, Bell, Liebherr and Yale/Hyster.
· Ertl – Ertl is one of the oldest die-cast truck manufacturers. Ertl’s primary focus is on farm equipment, and manufactures John Deere and Case/New Holland farm vehicles.
· Tonkin – Tonkin focuses on road trucks, primarily 18-wheelers, but their collection also includes log trucks and dump trucks.
· New Ray – New Ray Trucks also focus on road trucks, including 18-wheelers and pickup trucks, but their collection also includes specialty trucks such as garbage trucks and tanker trucks.
· Yatming – Yatming is a Hong Kong company that manufactures a wide line of fire trucks and police vehicles, in addition to its automobile lines.
· Corgi – Corgi is a British manufacturer that specializes in branded trucks and limited edition collectable vehicles.
· Tonka – Tonka trucks were manufactured more strictly as toys than many die-cast trucks made today. Tonka is currently owned by Hasbro, and now licenses the Tonka name to Maisto for die-cast vehicles. Today’s Tonka trucks include pickup trucks, farm tractors, big rigs and branded trucks.
Die-Cast Truck Scales
A scale refers to the ratio of the size of the model truck to the size of the actual truck. The primary scales for die-cast vehicles are 1:18, 1:24, 1:43, and 1:64. In a 1:18 scale truck, one inch on the die-cast truck translates to 18 inches on the actual truck. Some collectors prefer one scale of die-cast toy trucks, while other's collect trucks from a variety of scales.
Resources for Die-Cast Truck Collectors
The majority of resources for die-cast truck collectors are web sites created by die-cast truck manufacturers and sites developed by other collectors. While manufacturer web sites can easily be found with a simple search, it is more difficult to locate non-manufacturer resources. The following is a list of web sites for collectors by collectors:
· Uncle Chester’s Toy Trucks - http://unclechesterstoytrucks.com/
· S&K Toy Trucks - http://www.sktoytrucks.com/
· Diecast.Plus.com - http://www.diecast.plus.com/
· Spot-On - http://spot-on-collector.com/
Terminology (2)
Advanced Die-Casting Process Terminology
The article “Die-Casting Terminology” provided definitions for some basic die-casting process terms. This article will expand upon the earlier list to explain some of the more advanced terminology used to describe specific die-casting processes, tools, and parts. These terms may not be encountered as often by the hobbyist as the basic terms, but these definitions will provide a good understanding and appreciation of the intricacies of the die-casting process.
Biscuit – The biscuit consists of excess metal remaining in the shot sleeve of a cold chamber die casting machine. The biscuit is removed from the die with the casting after it has cooled.
Fillet – A fillet is a radius in an interior corner where two surfaces meet, rather than having a sharp corner. A fillet reduces the stresses that occur in that location when the part is bent or stressed.
Gate – A gate is a passage machined into the die that connects a runner to a die cavity.
Gooseneck – The gooseneck is the metal injection mechanism in a hot chamber die casting machine. It connects the metal chamber with the sprue hole via a nozzle.
Injection – Injection is the actual process by which the molten metal is forced into the die.
Insert – An insert is a piece of metal that is inserted into the die prior to casting. The insert then becomes part of the die-cast part.
Nozzle – The nozzle connects the gooseneck to the die via the sprue hole. The nozzle size defines the flow rate of the molten metal into the die during the casting process.
Plunger – The plunger is a piston that forces the molten metal into the die.
Port – The port is an orifice by which the molten metal enters the injection cylinder.
Runner – A runner is a passageway machined into the die that allows the molten metal to flow into the mold cavity. Molds that contain multiple cavities will have one runner directed to each cavity.
Shot Cylinder – In cold chamber die-casting, molten metal is drawn into the shot cylinder when the plunger is pulled out. In hot chamber die casting, the shot cylinder controls the plunger motion, but is not in contact with the molten metal.
Sprue – Sprue is the metal that fills the passage within the die between the part cavity and the injection nozzle after casting. This is waste metal that is removed from the part after it has cooled.
Sprue Pin – The sprue pin is a small cone-shaped part generally installed on the cover side of the die and is inserted into the sprue hole to deflect the incoming molten metal to spread it into different portions of the die. The sprue pin also makes it easier to remove the sprue after casting.
Undercut – An undercut is a feature of the die-cast part that prevents the piece from being ejected from the die after casting. Designs that require an undercut necessitate complex dies with removable slides so that the part can be extracted after casting. It is generally more cost effective to redesign the part to eliminate undercuts.
Waterline – A waterline is a channel built into the die that water can flow through. The water absorbs the heat from the die, accelerating the cooling process after the part has been cast.
Sources:
North American Die Casting Association web site - http://www.diecasting.org/
Totten, Funatani, and Xie, Handbook of Metallurgical Process Design, CRC Press, 2004.
The article “Die-Casting Terminology” provided definitions for some basic die-casting process terms. This article will expand upon the earlier list to explain some of the more advanced terminology used to describe specific die-casting processes, tools, and parts. These terms may not be encountered as often by the hobbyist as the basic terms, but these definitions will provide a good understanding and appreciation of the intricacies of the die-casting process.
Biscuit – The biscuit consists of excess metal remaining in the shot sleeve of a cold chamber die casting machine. The biscuit is removed from the die with the casting after it has cooled.
Fillet – A fillet is a radius in an interior corner where two surfaces meet, rather than having a sharp corner. A fillet reduces the stresses that occur in that location when the part is bent or stressed.
Gate – A gate is a passage machined into the die that connects a runner to a die cavity.
Gooseneck – The gooseneck is the metal injection mechanism in a hot chamber die casting machine. It connects the metal chamber with the sprue hole via a nozzle.
Injection – Injection is the actual process by which the molten metal is forced into the die.
Insert – An insert is a piece of metal that is inserted into the die prior to casting. The insert then becomes part of the die-cast part.
Nozzle – The nozzle connects the gooseneck to the die via the sprue hole. The nozzle size defines the flow rate of the molten metal into the die during the casting process.
Plunger – The plunger is a piston that forces the molten metal into the die.
Port – The port is an orifice by which the molten metal enters the injection cylinder.
Runner – A runner is a passageway machined into the die that allows the molten metal to flow into the mold cavity. Molds that contain multiple cavities will have one runner directed to each cavity.
Shot Cylinder – In cold chamber die-casting, molten metal is drawn into the shot cylinder when the plunger is pulled out. In hot chamber die casting, the shot cylinder controls the plunger motion, but is not in contact with the molten metal.
Sprue – Sprue is the metal that fills the passage within the die between the part cavity and the injection nozzle after casting. This is waste metal that is removed from the part after it has cooled.
Sprue Pin – The sprue pin is a small cone-shaped part generally installed on the cover side of the die and is inserted into the sprue hole to deflect the incoming molten metal to spread it into different portions of the die. The sprue pin also makes it easier to remove the sprue after casting.
Undercut – An undercut is a feature of the die-cast part that prevents the piece from being ejected from the die after casting. Designs that require an undercut necessitate complex dies with removable slides so that the part can be extracted after casting. It is generally more cost effective to redesign the part to eliminate undercuts.
Waterline – A waterline is a channel built into the die that water can flow through. The water absorbs the heat from the die, accelerating the cooling process after the part has been cast.
Sources:
North American Die Casting Association web site - http://www.diecasting.org/
Totten, Funatani, and Xie, Handbook of Metallurgical Process Design, CRC Press, 2004.
Sunday, February 17, 2008
Die-Casting Terminology
This is one of two posting for
Die-Casting Terminology
As with any manufacturing technique, the die-casting process has unique names and terminology. The following definitions clarify some of the terms that the hobbyist may encounter when researching die-cast parts.
Alloy – An alloy is a particular mix of metals used for a manufacturing process, such as die casting. Different alloys can provide different benefits, and a specific alloy for a part is chosen based on the required characteristics of the final part. These characteristics can include strength, hardness, shear strength, or electrical conductivity.
Blister – A blister is caused by a pocket of gas that is trapped in the mold near the surface of the casting during the casting process. A blister can look like a bubble in the surface of the die-cast part.
Blowhole – A blowhole is a void that occurs in heavy cast sections due to trapped gas during the casting process or shrinkage of the metal during cooling.
Cavity – A cavity is a concave surface within the interior of a die that will be filled with metal during the casting process.
Cold Chamber Casting - In a cold chamber machine, the molten metal is poured into a “cold” cylinder that is attached to the die. A hydraulic piston seals the cylinder and is used to force the metal into the die. The mechanism of a cold chamber machine is much like a caulking gun.
Die – A die, also referred to as a mold, serves as the pattern for the part to be created. The die contains the molten metal during injection, and holds the metal until it has cooled and hardened. Dies are generally manufactured from steel to withstand the temperatures of the molten metal alloys used in the die-casting process.
Draft – Draft is a slight angle designed into the vertical surfaces of the die to allow easier ejection of the part from the die after the die-casting process. Draft angles between 1º and 3º are common.
Flash – Flash is thin metal that surrounds the die-cast part where the two halves of the die were mated. Flash results from the molten metal seeping between the two halves of the die during injection and then hardening. Flash is generally removed post-casting using a trim die, or by using abrasives such as a grinding wheel. In many cases, particularly in aluminum castings, the flash can be recovered and recycled.
Hot Chamber Casting - In a hot chamber machine, the injection system sits in a bath of molten metal. A plunger is raised to pull molten metal into the injection chamber, and then pushed to inject the molten metal into the die. The mechanism of a hot chamber machine is much like a pneumatic bicycle pump, which pulls air in from around the pump and injects it into a tire through the tube and fitting.
Injection – Injection is the step in the die-casting process when the metal is forced under pressure into the prepared die.
Trim Die – A trim die is often used in post-casting processes to remove the flash from the edges of the die-cast component.
Void – A void is caused by a pocket of gas that is trapped in a thin section of a mold, resulting in a hole in the surface of the cast part.
Sources
North American Die Casting Association web site - http://www.diecasting.org/
Kinetic Die Casting web site - http://www.kineticdiecasting.com/
Die-Casting Terminology
As with any manufacturing technique, the die-casting process has unique names and terminology. The following definitions clarify some of the terms that the hobbyist may encounter when researching die-cast parts.
Alloy – An alloy is a particular mix of metals used for a manufacturing process, such as die casting. Different alloys can provide different benefits, and a specific alloy for a part is chosen based on the required characteristics of the final part. These characteristics can include strength, hardness, shear strength, or electrical conductivity.
Blister – A blister is caused by a pocket of gas that is trapped in the mold near the surface of the casting during the casting process. A blister can look like a bubble in the surface of the die-cast part.
Blowhole – A blowhole is a void that occurs in heavy cast sections due to trapped gas during the casting process or shrinkage of the metal during cooling.
Cavity – A cavity is a concave surface within the interior of a die that will be filled with metal during the casting process.
Cold Chamber Casting - In a cold chamber machine, the molten metal is poured into a “cold” cylinder that is attached to the die. A hydraulic piston seals the cylinder and is used to force the metal into the die. The mechanism of a cold chamber machine is much like a caulking gun.
Die – A die, also referred to as a mold, serves as the pattern for the part to be created. The die contains the molten metal during injection, and holds the metal until it has cooled and hardened. Dies are generally manufactured from steel to withstand the temperatures of the molten metal alloys used in the die-casting process.
Draft – Draft is a slight angle designed into the vertical surfaces of the die to allow easier ejection of the part from the die after the die-casting process. Draft angles between 1º and 3º are common.
Flash – Flash is thin metal that surrounds the die-cast part where the two halves of the die were mated. Flash results from the molten metal seeping between the two halves of the die during injection and then hardening. Flash is generally removed post-casting using a trim die, or by using abrasives such as a grinding wheel. In many cases, particularly in aluminum castings, the flash can be recovered and recycled.
Hot Chamber Casting - In a hot chamber machine, the injection system sits in a bath of molten metal. A plunger is raised to pull molten metal into the injection chamber, and then pushed to inject the molten metal into the die. The mechanism of a hot chamber machine is much like a pneumatic bicycle pump, which pulls air in from around the pump and injects it into a tire through the tube and fitting.
Injection – Injection is the step in the die-casting process when the metal is forced under pressure into the prepared die.
Trim Die – A trim die is often used in post-casting processes to remove the flash from the edges of the die-cast component.
Void – A void is caused by a pocket of gas that is trapped in a thin section of a mold, resulting in a hole in the surface of the cast part.
Sources
North American Die Casting Association web site - http://www.diecasting.org/
Kinetic Die Casting web site - http://www.kineticdiecasting.com/
Introduction to the Die-Casting Process
Introduction to the Die-Casting Process
Die-casting, by definition, is a process in which molten metal is injected into metallic molds under pressure to form objects. The molds, which are generally made of steel and referred to as “dies”, can be designed to create very detailed parts with little or no post-machining required after production. Die-casting is analogous in many ways to plastic injection molding. Dies can be reused multiple times because the temperatures of the molten metal are not high enough to affect the steel die. Die-cast parts are generally lightweight, and for this reason are often used in aircraft and automobile applications.
History of the Die-Casting Process
Die-casting by pouring molten metal into a die, also known as the gravity pressure method, is a manufacturing method that has been used for hundreds of years. The more modern method of pressure injection die casting was patented in the mid-1800’s to create lead printer’s type. The use of die-casting as a manufacturing technique exploded in the early 1900’s, particularly when zinc and aluminum alloys became more readily available. Today, die-casting is a process used for a wide range of products and applications.
Materials Used in Die-Casting
In order to preserve the integrity of the die, and allow it to be used for many castings, only alloys with relatively low melting temperatures can be used in the die casting process. Historically, lead and tin were the primary materials for die-cast parts, since they could easily be melted using conventional processes. Today, the majority of die-cast parts are created from aluminum or zinc alloys, but other metals such as magnesium or copper can be used. Each alloy delivers its own benefits, and therefore the product requirements drive the material choice. Aluminum can be found in aircraft and automobile parts, while copper may be used for parts that must conduct electricity.
Description of the Die-Casting Process
Before casting is performed, the mold is assembled. A mold can consist of two or more parts, depending on the complexity of the part being fabricated. Die-casting machines are categorized as either cold chamber machines or hot chamber machines. In a cold chamber machine, the molten metal is poured into a “cold” cylinder that is attached to the die. A hydraulic piston seals the cylinder and forces the metal into the die. In a hot chamber machine, the injection system sits in a bath of molten metal. A plunger is raised to pull molten metal into the injection chamber, and then pushed to inject the molten metal into the die. The mechanism of a hot chamber machine is much like a pneumatic bicycle pump, which pulls air in from around the pump and injects it into a tire through the tube and fitting.
After the casting process, the part may have flash, or thin metal around the part where the two halves of the die come together, around it. The flash is removed during post-machining processes. Some die-cast parts are plated or painted after manufacture for appearance, but the surface of die-cast parts are generally very smooth and hold fine detail.
Examples of Die-Cast Components
Many plumbing fixtures, such as bathtub spouts, are manufactured from zinc alloys using a die-casting process and then plated with a chrome coating. Lightweight aircraft components can be die-cast from aluminum alloys. Other examples include heat sinks with complex shapes and large surface areas for electronic components, lightweight aluminum automobile parts, and lighting fixtures. Die-cast parts require very little post-manufacturing machining, saving time and labor costs in the manufacturing process.
Die-casting is a manufacturing process used for a variety of applications, including toys. In the Napoleonic era, gravity pressure methods were used to cast lead military figures. Die-cast vehicles have been available nearly as long as the vehicles themselves have existed. Early die cast manufacturers existing at the turn of the 20th century include Meccano in the United Kingdom and Dowst Brothers in the United States. Companies such as Ertl have been producing die-cast farm vehicles since 1945.
Sources
North American Die Casting Association web site - http://www.diecasting.org/
Wikipedia – http://www.wikipedia.org
Toy Wonders web site - http://www.toywonders.net/history/wikipedia/diecast_car.htm
Die-casting, by definition, is a process in which molten metal is injected into metallic molds under pressure to form objects. The molds, which are generally made of steel and referred to as “dies”, can be designed to create very detailed parts with little or no post-machining required after production. Die-casting is analogous in many ways to plastic injection molding. Dies can be reused multiple times because the temperatures of the molten metal are not high enough to affect the steel die. Die-cast parts are generally lightweight, and for this reason are often used in aircraft and automobile applications.
History of the Die-Casting Process
Die-casting by pouring molten metal into a die, also known as the gravity pressure method, is a manufacturing method that has been used for hundreds of years. The more modern method of pressure injection die casting was patented in the mid-1800’s to create lead printer’s type. The use of die-casting as a manufacturing technique exploded in the early 1900’s, particularly when zinc and aluminum alloys became more readily available. Today, die-casting is a process used for a wide range of products and applications.
Materials Used in Die-Casting
In order to preserve the integrity of the die, and allow it to be used for many castings, only alloys with relatively low melting temperatures can be used in the die casting process. Historically, lead and tin were the primary materials for die-cast parts, since they could easily be melted using conventional processes. Today, the majority of die-cast parts are created from aluminum or zinc alloys, but other metals such as magnesium or copper can be used. Each alloy delivers its own benefits, and therefore the product requirements drive the material choice. Aluminum can be found in aircraft and automobile parts, while copper may be used for parts that must conduct electricity.
Description of the Die-Casting Process
Before casting is performed, the mold is assembled. A mold can consist of two or more parts, depending on the complexity of the part being fabricated. Die-casting machines are categorized as either cold chamber machines or hot chamber machines. In a cold chamber machine, the molten metal is poured into a “cold” cylinder that is attached to the die. A hydraulic piston seals the cylinder and forces the metal into the die. In a hot chamber machine, the injection system sits in a bath of molten metal. A plunger is raised to pull molten metal into the injection chamber, and then pushed to inject the molten metal into the die. The mechanism of a hot chamber machine is much like a pneumatic bicycle pump, which pulls air in from around the pump and injects it into a tire through the tube and fitting.
After the casting process, the part may have flash, or thin metal around the part where the two halves of the die come together, around it. The flash is removed during post-machining processes. Some die-cast parts are plated or painted after manufacture for appearance, but the surface of die-cast parts are generally very smooth and hold fine detail.
Examples of Die-Cast Components
Many plumbing fixtures, such as bathtub spouts, are manufactured from zinc alloys using a die-casting process and then plated with a chrome coating. Lightweight aircraft components can be die-cast from aluminum alloys. Other examples include heat sinks with complex shapes and large surface areas for electronic components, lightweight aluminum automobile parts, and lighting fixtures. Die-cast parts require very little post-manufacturing machining, saving time and labor costs in the manufacturing process.
Die-casting is a manufacturing process used for a variety of applications, including toys. In the Napoleonic era, gravity pressure methods were used to cast lead military figures. Die-cast vehicles have been available nearly as long as the vehicles themselves have existed. Early die cast manufacturers existing at the turn of the 20th century include Meccano in the United Kingdom and Dowst Brothers in the United States. Companies such as Ertl have been producing die-cast farm vehicles since 1945.
Sources
North American Die Casting Association web site - http://www.diecasting.org/
Wikipedia – http://www.wikipedia.org
Toy Wonders web site - http://www.toywonders.net/history/wikipedia/diecast_car.htm
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