Core plugs, also called freeze plugs or Welch plugs, are used to fill the sand casting core holes found on water-cooled internal combustion engines.
Core plugs, also called freeze plugs or Welch plugs, are used to fill the sand casting core holes found on water-cooled internal combustion engines.
Sand cores are used to form the internal cavities when the engine block or cylinder head(s) is cast. These cavities are usually the coolant passages. Holes are designed into the casting to support internal sand forms and to facilitate the removal of the sand after the casting has cooled. These holes have no purpose after the sand has been removed. A core plug is a cap at the end of these passages used to prevent water or coolant leaking from the engine. [1]
Core plugs are usually thin metal cups press fitted into the casting holes, but may be made of rubber or other materials. The most common metal plugs used in automotive engines are made from plated mild steels, stainless steels, brass or bronze. In some high-performance engines the core plugs are large diameter cast metal threaded pipe plugs. [2]
Core plugs can often be a source of leaks due to corrosion caused by cooling system water. [3] Although modern antifreeze chemicals do not evaporate and may be considered "permanent", anti-corrosion additives gradually deplete and must be replenished via a flush and refill. Automotive manufacturers specify time and mileage numbers for cooling system maintenance in their published factory maintenance manuals.
The slang term "freeze plug" was coined many decades ago out of ignorance of the true purpose of the core plugs - they were never designed to be displaced by water freezing inside the block due to a lack of an anti-freeze/water mixture and their displacement is merely coincidental if freezing does occur. The sole purpose of a core plug is to literally act as a plug in the holes designed to be in a casting which allows the casting sand to be removed during the manufacture process. [4]
The Welch plug is a type of core plug that is made from a thin disc of metal. The Welch plug is dome-shaped and inserted into the casting hole with the convex side facing outwards. [5] When installed by striking the Welch plug with a hammer, the dome collapses slightly, expanding it laterally to seal the hole. This differs from other dish-shaped core plug designs, which form a seal when their tapered sides are pressed into the casting hole. [6]
The Welch plug was originally designed in the 1900s at the Welch Motor Car Company in the United States. Prior to the invention of the Welch plug, the core holes were sealed using pipe plugs. During the testing of a car, one of the pipe plugs backed out. In order to get back on the road, one of the Welch brothers installed a press-fit quarter or half dollar coin into the hole using a hammer. The design of the Welch plug was refined based on this principle of a press-fit metallic disc. [7]
In metalworking and jewelry making, casting is a process in which a liquid metal is delivered into a mold that contains a negative impression of the intended shape. The metal is poured into the mold through a hollow channel called a sprue. The metal and mold are then cooled, and the metal part is extracted. Casting is most often used for making complex shapes that would be difficult or uneconomical to make by other methods.
A radiator is a heat exchanger used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in cars, buildings, and electronics.
A heat pipe is a heat-transfer device that employs phase transition to transfer heat between two solid interfaces.
Water cooling is a method of heat removal from components and industrial equipment. Evaporative cooling using water is often more efficient than air cooling. Water is inexpensive and non-toxic; however, it can contain impurities and cause corrosion.
An antifreeze is an additive which lowers the freezing point of a water-based liquid. An antifreeze mixture is used to achieve freezing-point depression for cold environments. Common antifreezes also increase the boiling point of the liquid, allowing higher coolant temperature. However, all common antifreeze additives also have lower heat capacities than water, and do reduce water's ability to act as a coolant when added to it.
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In a reciprocating engine, the cylinder is the space in which a piston travels.
Sand casting, also known as sand molded casting, is a metal casting process characterized by using sand — known as casting sand — as the mold material. The term "sand casting" can also refer to an object produced via the sand casting process. Sand castings are produced in specialized factories called foundries. In 2003, over 60% of all metal castings were produced via sand casting.
A block heater is used in cold climates to warm an engine prior to starting. They are mostly used for car engines; however, they have also been used in aircraft engines.
In an internal combustion engine, the engine block is the structure which contains the cylinders and other components. In an early automotive engine, the engine block consisted of just the cylinder block, to which a separate crankcase was attached. Modern engine blocks typically have the crankcase integrated with the cylinder block as a single component. Engine blocks often also include elements such as coolant passages and oil galleries.
A steam generator is a heat exchanger used to convert water into steam from heat produced in a nuclear reactor core. They are used in pressurized water reactor between the primary and secondary coolant loops.
The Family II is a straight-4 piston engine that was originally developed by Opel in the 1970s, debuting in 1981. Available in a wide range of cubic capacities ranging from 1598 to 2405 cc, it simultaneously replaced the Opel CIH and Vauxhall Slant-4 engines, and was GM Europe's core mid-sized powerplant design for much of the 1980s, and provided the basis for the later Ecotec series of engines in the 1990s.
In casting, a pattern is a replica of the object to be cast, used to form the sand mould cavity into which molten metal is poured during the casting process. Once the pattern has been used to form the sand mould cavity, the pattern is then removed, Molten metal is then poured into the sand mould cavity to produce the casting. The pattern is non consumable and can be reused to produce further sand moulds almost indefinitely.
The wax thermostatic element was invented in 1934 by Sergius Vernet (1899–1968). Its principal application is in automotive thermostats used in the engine cooling system. The first applications in the plumbing and heating industries were in Sweden (1970) and in Switzerland (1971).
An expansion tank or expansion vessel is a small tank used to protect closed water heating systems and domestic hot water systems from excessive pressure. The tank is partially filled with air, whose compressibility cushions shock caused by water hammer and absorbs excess water pressure caused by thermal expansion.
Radiators are heat exchangers used for cooling internal combustion engines, mainly in automobiles but also in piston-engined aircraft, railway locomotives, motorcycles, stationary generating plant or any similar use of such an engine.
A core is a device used in casting and moulding processes to produce internal cavities and reentrant angles. The core is normally a disposable item that is destroyed to get it out of the piece. They are most commonly used in sand casting, but are also used in die casting and injection moulding.
A monobloc or en bloc engine is an internal-combustion piston engine some of whose major components are formed, usually by casting, as a single integral unit, rather than being assembled later. This has the advantages of improving mechanical stiffness, and improving the reliability of the sealing between them.