Metal Casting Zone Info Blog

Ann Knapp asked:


Intake and Exhaust Manifolds are critical components of automobile engines responsible for supplying the fuel/air mixture to the engine (intake) and collecting the gases for expulsion (exhaust). They need to be clean and functioning in order for a car to operate at peak efficiency. Problems with the manifolds can result in costly repair and poor performance. Therefore, cleaning these parts before they are added to the engine is a high priority for auto manufacturers and suppliers.

Intake Manifolds
The intake manifold has a high specification of cleanliness. Since the manifold supplies the engine, it must be clean. Debris and contamination in the manifold can be hazardous to the engine, clogging the engine and damaging the car. Metal chips left over from the production process need to be eliminated in order for the manifold to pass inspection by the manufacturer.

Intake manifolds are often made of soft metals, such as aluminum or magnesium. As such, they require specific cleaning chemistry. When selecting a chemistry to use for cleaning the intake manifold, it is important that the chemistry can effectively clean the manifold without damaging the soft metal construction. Further, the chemistry must not create hydrogen during the cleaning process, because that can result in an explosion.

A common specification for contamination in intake manifolds is in the 1.5mg range. A filter weight test is used to measure the level of contamination. Depending on the design of the manifold, both immersion and spray systems can be effective in reaching this specification. These methods can both produce manifolds with contamination weights less than 1.5mg, usually clearing the standard quite comfortably.

Exhaust Manifolds
The exhaust manifold also needs to be cleaned, but often the specifications are not as stringent as for intake manifolds. This is because the exhaust manifold is located downstream from the engine, meaning it does not provide any material for the engine. Rather, it collects gas from the engine and expels it. There are exceptions to this general rule. If a turbocharger is present, it will be located downstream from the exhaust manifold. In this case, the exhaust manifold must reach cleanliness levels comparable to the intake manifold, or the turbocharger will be contaminated.

These manifolds are usually constructed from cast iron, and sometimes cast stainless steel. Exhaust manifolds must pass a smoke test before the manufacturer accepts them. A smoke free performance in the test is required by ISO 14001 standards that auto manufacturers adhere to. Rust inhibitors are also necessary to prevent excessive rust. Rust inhibition applies to the cast iron models; a stainless steel manifold, obviously, does not have the same rust concerns. Many manifolds are imported from foreign manufacturers, and therefore American based auto manufacturers require them to be thoroughly inspected and tested to ensure that the foreign production has met the domestic standards in place.

Washer Solutions
For intake manifolds, there is often a specific area of chips and coolant that needs to be removed. These contaminated areas can be cleaned easily and quickly with a custom washer. By using a custom-rotating fixture, along with spray headers targeted specifically for the part, the manifold can meet cleanliness specifications. The fixture will rotate to the locations of the contamination to target individual orifices and enhance cleaning. By rotating in a full circle, optimal drainage and drying can be achieved.

Exhaust manifolds do not require the same level of specificity. For these manifolds, a washer needs to be able to remove chips form the manifold along with applying a rust inhibitor and drying the parts to virtually “bone dry”. One way of achieving this goal is a fixtured indexing washer. The system removes contaminant first. After that, a rust inhibitor is applied to protect the manifold. Then a blow dry process leaves the parts dry enough for specifications.

By including multiple filtration features, the part can be cleaned effective. This process includes a special chip basket filter in the fluid that removes the chips via a flush and then returns the part to the process.

These solutions will not work for every situation. However, by working with a qualified and experienced washer manufacturer, a company in need of manifold cleaning will certainly be able to custom design a machine that works to the specifications they require. Producing clean, quality manifolds is important and necessary. Finding a custom washer to assist in the process will go a long way in maintaining the high level of quality required to produce for American auto manufacturers.

Metal Casting Forum

Kent Kelin asked:


Casting is a process in which liquid material made from heating metals, is poured in a module, to give the liquid a desired shape. Then the liquid is cooled and a solid object in the desired shape and size is obtained. Casting Jewelry is the latest “in-thing” in the fashion markets. This jewelry is made from different materials like silver, aluminum, gold, bronze, alloy metals and even plated casting jewelry is available.

Casting Jewelry is very attractive and delicate. They are made using machines, but very finely crafted and hand made jewelry is also available in the market. This type of jewelry can be available at a very low, as well as high costs, depending on the design and material and design that you choose. Casting Jewelry is very fragile and should be handled with out most care as it can break easily. With the advent of casting jewelry, the fashion world has benefited a great deal. Today, free flowing designs, multicolored jewelry and even a special made to order jewelry is available in the market.

Before this, it was difficult to cast a metal in a desired shape but today it is as simple as it gets, all you need is a creative mind to create new designs and a group of well qualified workers and good machinery to make your own casting jewelry. This also gives you an option to make your own series of new designs. Casting jewelry is being widely used across the globe. With the prices of gold increasing day by day and with the entry of new metal jewelry like platinum, casting jewelry slowly but surely is making a mark in the fashion world. With the cost silver plated casting jewelry, the dream of wearing a new necklace or a new ear-ring everyday is a reality. You can actually afford new set of jewelry everyday. There are also costly models made of pure gold and delicate designs and with embedded diamonds that are available.

Casting Jewelry is not only about fashion, it has also opened a new avenue for small scale businesses. With proper knowledge and machinery, you can start your own company and make casting jewelry. It does not need any expensive material nor does it need a big capital. A small store room in your house will also be sufficient to set up your casting jewelry work-shop. You can then design your own range or hire a professional jewelry designer to create your range of jewelry.

Casting Jewelry has also helped the educational branch of “jewelry designing” grow considerably. Today it is considered in par with “fashion designing”. Many young students are nowadays looking at jewelry designing as a full time career.

The only draw-back of plated casting jewelry is that is they are used on daily basis, then they might lose their shine and the coated silver or gold respectively. If they come in contact with water regularly, then they can turn black. You can get them re-plated and use them. As casting jewelry is very fragile and delicate, even a slight mishap can change its shape or even break it.

Backyard Metal Casting

Kent Kelin asked:


Brass casting, as the name suggests, involves the use of brass as the molten metal. Brass casting can be carried out by the way of sand casting only. Sand casting can be defined as a ‘cast part’ produced by formation of a mold from a mixture of sand and pouring the casting liquid (mostly molten metal) into mold. Then the air-cooling of the mold takes place. After the solidification of metal, the removal of mold takes place. The metal used here is brass. It is a known fact that brass is an alloy of copper and zinc. Hence, to be precise, the molten metal consists of two elements.

Sand molding consists of two types- ‘Green sand’ molding and ‘air set’ molding. The first one consists of a blend of moisture, clay, silica sand and other additives. The second one makes use of dry sand bonded to all the above materials except moist clay, by the way of using an adhesive, which is fast curing.

At times, there is a placing of a temporary plug (in the mold cavity) to enable the formation of a channel to pour the fluid which is to be molded. The molds of the second type, i.e. the air-set molds result in the formation of a 2-part mold. The two parts are bottom and top. The tamping-down of the sand mixture takes place as it gets added. Many a times, the final assembly of the mold is vibrated to get the sand compacted and get the unwanted voids filled. Then the molten alloy (brass) gets poured into mold. After the solidification and cooling of brass, the separation of casting from sand mold takes place. Normally, such molds are one-time usable.

Patterns: A designer or an engineer provides the design of the object to be produced. On the basis of this design, a pattern is built by an efficient pattern maker by the use of plastic, metal, or wood. Polystyrene can also be used. The casting brass would get contracted during solidification. Non-uniformity can also result out of this. Therefore, the size of the pattern should be a bit larger as compared to the final product. ‘Contraction Allowance’ is the name given to this difference. Brass enters the mold cavity through a runner system including sprue and other feeders.

Molding box: A molding box having multiple parts (also known as casting flask whose bottom and top halves are called drag and cope respectively) is constructed for receiving the pattern. There may be an addition of sand to nullify the defects introduced due to the pattern getting removed.

Chills: To have a proper control over metallurgical structure and solidification of brass, plates of brass, or any other metal can be placed in mold. A hard structure may get formed at these places. Chills can be used for promoting directional solidification as well.

Design Requirements: The thing in making and the pattern corresponding to it should be designed in such a way that every stage of process can get accommodated. One should be able to take away the pattern without causing any disturbance to molding sand.

Hobby Metal Casting

Kent Kelin asked:


There are various casting processes being implemented now days. The oldest amongst them is sand casting. Spin casting is also widely used. They can be described as follows:

Sand Casting: Sand casting involves formation of mold from a mixture of sand and to pour a casting liquid, most probably, a molten metal into mold. The metal is then allowed to solidify and the removal of mold, takes place. Sand molding consists of two types: green sand method and air set method. The first one consists of mixture of clay, moisture, silica, and many other additives. The second one consists of mixture of dry sand and other materials, not moist clay. They are mixed with the help of a quick curing adhesive. The collective use of these materials is called ‘air set’.

At times, there is temporary plug placed to pour the fluid which is to be molded. Air-set molds usually form molds consisting of two parts-the bottom and the top. The mixture of sand gets tamped down after its addition. It does not generate any by-product. After the solidification and cooling of metal, the mold gets usually destroyed. This is because its removal involves a lot of breaking and cracking. The casting accuracy depends a great deal on the sand and the process of molding used. Castings composed of green sand result into formation of rough texture on casting surface, and this characteristic makes them easily recognizable. Air-set molds produce smoother castings.

Many a times, the casting process results in losing of components of sand mixture. It is possible to reuse green sand by the way of adjusting the composition to get the lost additives and moisture replenished. The entire pattern itself is eligible to be reused for producing novel sand molds. The method of reuse can be continued for an indefinite period. In 1950, casting process got automated partially. They have been in great demand for developing production lines since then.

Spin Casting: Spin Casting is better known as Centrifugal Rubber Mold Casting (CRMC). It implies utilization of centrifugal force for producing castings out of rubber mold. As a customary practice, a mold having shape of a disc gets spun through its ‘central axis’ at a pre-decided speed. The material used for casting is usually thermoset plastic in the liquid form or a molten metal. It gets poured into the mold through the opening at its centre. Corresponding to the solidification of metal, or the setting of thermoset plastic, the spinning of the filled mold takes place.

Normally, organic rubber or vulcanized silicone is used as a mold-making substrate in spin casting. Vulcanization takes place in the middle of process of mold-making. After the successful completion of vulcanization process, venting and gating must be undergone by the mold. This implies carving of channels for ensuring proper material flow and air during the course of casting. A scalpel or knife is used to carry out the above two processes. The mold complexity is directly proportional to the time required in implementation of venting and gating.

Metal Casting Basics

Kent Kelin asked:


Bronze has been the most sought-after metal for cast metal sculptures in the bygone years. Bronze alloys have a desirable and unusual property to expand slightly prior to their setting. This helps a great deal in filling every corner of the mold. Their ductility and strength causes them to be molded into any form. However, bronze has a basic disadvantage of not being durable. Hence, there are hardly any traces of ancient bronze statues found. Bronze casting generally takes place by a process called lost-wax casting. Though, centrifugal and sand castings are also employed, around 90% of bronze casting takes place through lost-wax casting.

Lost-wax method: Lost-wax casting, in the industry, is better known as investment casting. It is costlier than die and sand casting, but outshines them in terms of accuracy. It is easily possible to make complicated structures through ‘lost-wax casting’. The process can be described as follows:

Sculpting: First, the original artwork is created by the artist from clay, wax, or some other material. Mostly, clay (oil-based) and wax are used due to their property of retention of softness.

Mold making: Majority of molds consist of 2 pieces, along with a shim placed between 2 halves at the time of construction in order to put back the mold accurately. Keys are kept in the shim. The small sculpture molds generally consist of plaster. Fiberglass can also be used. To have the minute details preserved on the surface of original artwork, there exists a mold inside. It is made up of vinyl, silicone, or latex supported by plaster part of mold. Generally, the destruction of original artwork takes place during making. This is due to the solid nature of the originals. The other reason is the rigidity of the originals at the time of removal of plaster mold. That’s why; the original is cut off into thin, long pieces and separately molded. At times, a number of molds are required for recreating the original structure.

Wax: After the completion of latex-and-plaster mold, the pouring of molten wax takes place. Then, swishing is carried out till a uniform coating is obtained. The thickness of the coating is 1/8 inches. The mold’s inner surface gets covered by it. This process is repeatedly executed till the preferred thickness is attained.

Wax removal: Artwork’s ‘hallow wax copy’ is detached from mold. This mold may be reused by the artist for making more copies of wax, but its use gets restricted due to frequent ‘wear & tear’. Around 25 copies can be made for tiny bronze artworks.

Chasing: The chasing of each copy starts. Rubbing of the marks is done by a hot metal tool. The marks showing ‘flashing’ or ‘parting line’ are rubbed out.

Spruing: The spruing of copy generates paths to flow (for molten bronze) and causes air to move out.

Slurry: The dipping of sprued copy into a liquid silica slurry, and then into sand-like ‘stucco’ takes place. This process is repeatedly carried out till the coating attains thickness of at least ½ inch.

After these steps, the out-and-out processes like burnout, testing, pouring, releasing, metal chasing, and patinating are carried out.

Metal Casting Basics

Kent Kelin asked:


There are several types of casting furnaces which include Electric Arc furnaces, Blast furnaces, Cornwall Iron Furnace, etc. Here’s a quick review of some of them.

Electric Arc Furnace: This furnace can be described as a furnace heating charged materials by the way of an electric arc. These furnaces exist in all the sizes-right, from the smallest one having a capacity of around 1 ton to the largest one having a capacity of 400 tons. The former one is used in foundries to produce cast iron products, whereas the latter one is used for secondary steel making. The ones used by dentists and in research laboratories might be having capacity of a few grams only. The electric arc furnace can have temperatures risen up to 1800 Celsius. The first electric furnaces came into being in 1907, at the hands of Paul Heroult of French origin. The commercial part of these furnaces was established in the United States of America. In the beginning, the specialty product used in the making of spring steel and machine tools was electric steel. Calcium Carbide was also prepared in these arc furnaces. It (calcium carbide) was used in carbide lamps.

This furnace comprises of a refractory-lined vessel, normally water-cooled in huge sizes, having a covering of a retractable roof, through which the entry of graphite electrodes takes place. They might be one or many in number. The furnace is divided into 3 sections: the shell, consisting of lower steel bowl and sidewalls, the hearth, consisting of refractory lining the lower bowl, and the roof, that can be water-cooled or refractory-lined, and can easily be shaped into a spherical section or conical section (frustum). A refractory delta is also supported by the roof at its center, by the way of which graphite electrodes make an entry.

The process of operation starts with delivery of scrap metal to scrap bay which is located adjoining melt shop. After that, the loading of scrap into huge buckets or baskets takes place. The next step is to carry this basket to the melt shop. The charging takes place here. After the completion of charging, let the electrodes be allowed to enter and placed onto scrap. This causes the arc to be struck. Lower voltage is preferred for this part (of operation) to provide protection to the walls and roof against arc damage and excessive heat. After having the electrodes reached the heavy melt, shielding of arcs by scrap takes place. This enables a rapid formation of molten pool, thereby decreasing tap-to-tap times. Oxygen is also allowed to enter.

Blast Furnace: It can be referred to as a kind of metallurgical furnace, through which the process of smelting takes place. This produces metals, normally iron. These furnaces trace their origin to China (around 500 BC). They were also found in Belgium and England later. They do not have any special mode of operation. The metals get melted by heating only. Generally, iron is melted in these furnaces. The chemical reaction can be explained as follows:

Fe2O3 + 3CO -> 2Fe + 3CO2

Iron Metal Casting

Kent Kelin asked:


Lost Wax Casting is known as Cire Perdue in French. It is a process in which an artist’s sculpture is used to cast bronze. The Lost Wax Casting method is also known as Investment Casting in the modern industrial world. This is a very ancient method used for casting small bronze sculptures, but today it is used to make many different artifacts and the process varies from foundry to foundry. Today this developed method of Lost Wax Casting is used to make articles like fine jewelery, show pieces, dental restoration, a few specific industrial parts and also some machine tools.

Process of Lost Wax Casting:

Rough Sculptor making: A creative artist makes an original sculptor or mold or an artwork by using raw material like wax, plaster of Paris or clay. A mixture of oil based clay and wax is preferred as these materials retain their softness.

Final Mold Making: A mold is then made as per the original sculptor. The mold is made up of two pieces and a key with shim is placed between the two pieces during construction so the mold can be put accurately back together. Molds are generally made using plaster or fiberglass or any other material that may be suitable. An inner mold of latex or vinyl or silicone is put pup preserve the details of the original art work. Generally, the original art work made of plaster mold cracks and breaks during the initial phase of deconstruction. Many a times, numerable molds are required to get the exact replica of the original art work.

Filling up the mold: Once the latex and plaster mold is complete and finished, molten wax is poured into the mold till it gets an even coating all around the mold. The thickness of the wax coating is around 1/8 inch. This process is then repeated until the desired thickness is achieved.

Removal of wax replica: The hollow wax replica of the original art work is then removed from the mold. The original mold can be used for making more wax replicas, but due to the wear and tear of the original mold the reuse of the mold is limited.

Softening: Each wax mold is then chased or softened using heated metal tools. The metal tools are rubbed around portions that show cracks or the joining line of the mold, where the pieces have come together. Separately molded wax pieces are then heated and attached. The finished mold is then dressed in order to hide any imperfections. The final piece then looks like a bronze sculpture.

Making paths for molten bronze: It is also known as “spuring”, in short the wax copy is then branched with treelike wax, so that the molten bronze reaches the right parts and also it helps the air to escape. The critical and careful spuring begins from the top of the wax copy. The top of the copy is attached to by wax cylinders to different points on the wax copy.

Slurry, burnout, testing, pouring, release, metal-chasing, and painting are the final steps in the process of Lost Wax Casting.

Hobby Metal Casting

Kent Kelin asked:


Oxy-fuel cutting and oxy-fuel welding can be described as the processes of using oxygen and fuel gases to either cut or weld metals. There are some striking differences between these two processes. In the first process, a cutting torch is made use of for heating ferrous metal to a temperature of around 980 degree Celsius. An oxygen stream is being trained on a hot metal that combines with iron chemically which later flows from the kerfs, or cut in the form of slag of iron oxide. In the second process, a ‘welding torch’ is made use of for welding metals.

Torches that burn the inside fuel with air (atmosphere) cannot be termed as oxy-fuel torches. They stand out owing to the use of single tank. This is because oxy-fuel cutting/welding requires oxygen, fuel, and two tanks. It’s not possible to melt some of the metals with single-tank torches. Hence, these torches can be used for brazing and soldering, but not for welding. A metal-cutting torch is better known as hot blue spanner, blue wrench, hot wrench, smoke wrench, and gas-axe.

Types of Torches: The torch can be defined as the part held and manipulated by the welder to get the weld made. It possesses a valve and connection for oxygen and the same things for fuel gas, a handle to obtain the grip, an integrating chamber (angularly set) where there occurs a mixing of oxygen and fuel gas, with a tip where formation of flame takes place. The fuel gases used along with oxygen include propylene, propane, hydrogen gas, MAPP gas, Liquefied Petroleum Gas (LPG), and the most widely used is acetylene.

Injector Torch: It can be defined as an archetypal oxy-fuel torch, also known as an equal-pressure torch. It carries out the mixing of mere two gases. The injector torch operates in such a way that high pressure oxygen comes out of the tiny nozzle present in the torch head, and the fuel gas gets dragged towards it via the venturi effect.

Rose-bud Torch: The use of this torch is to carry out the heating of metals for straightening, bending, etc. It is generally used where a huge area requires heating. It produces a rose-bud shaped flame at the end, hence the name. This torch can carry out the function of heating small areas like rusted bolts and nuts as well. However, here, filler rod won’t be used with torch.

Cutting Torch: The head of the cutting torch is used for cutting metal. Its identification details are as follows: The inside of the torch consists of a combination of oxygen and acetylene. It helps in producing flame of a high temperature. It consists of 3 pipes going to a nozzle at 90 degree. It also contains an oxygen-blast trigger which blasts away the material during its cutting by the way of providing oxygen.

Welding Torch: The welding torch consists of either 1 or 2 pipes running towards the nozzle without oxygen-blast trigger. As the name suggests, it performs the function of welding.

Brass Metal Casting

Kent Kelin asked:


There are several types of casting furnaces which include Electric Arc furnaces, Blast furnaces, Cornwall Iron Furnace, etc. Here’s a quick review of some of them.

Electric Arc Furnace: This furnace can be described as a furnace heating charged materials by the way of an electric arc. These furnaces exist in all the sizes-right, from the smallest one having a capacity of around 1 ton to the largest one having a capacity of 400 tons. The former one is used in foundries to produce cast iron products, whereas the latter one is used for secondary steel making. The ones used by dentists and in research laboratories might be having capacity of a few grams only. The electric arc furnace can have temperatures risen up to 1800 Celsius. The first electric furnaces came into being in 1907, at the hands of Paul Heroult of French origin. The commercial part of these furnaces was established in the United States of America. In the beginning, the specialty product used in the making of spring steel and machine tools was electric steel. Calcium Carbide was also prepared in these arc furnaces. It (calcium carbide) was used in carbide lamps.

This furnace comprises of a refractory-lined vessel, normally water-cooled in huge sizes, having a covering of a retractable roof, through which the entry of graphite electrodes takes place. They might be one or many in number. The furnace is divided into 3 sections: the shell, consisting of lower steel bowl and sidewalls, the hearth, consisting of refractory lining the lower bowl, and the roof, that can be water-cooled or refractory-lined, and can easily be shaped into a spherical section or conical section (frustum). A refractory delta is also supported by the roof at its center, by the way of which graphite electrodes make an entry.

The process of operation starts with delivery of scrap metal to scrap bay which is located adjoining melt shop. After that, the loading of scrap into huge buckets or baskets takes place. The next step is to carry this basket to the melt shop. The charging takes place here. After the completion of charging, let the electrodes be allowed to enter and placed onto scrap. This causes the arc to be struck. Lower voltage is preferred for this part (of operation) to provide protection to the walls and roof against arc damage and excessive heat. After having the electrodes reached the heavy melt, shielding of arcs by scrap takes place. This enables a rapid formation of molten pool, thereby decreasing tap-to-tap times. Oxygen is also allowed to enter.

Blast Furnace: It can be referred to as a kind of metallurgical furnace, through which the process of smelting takes place. This produces metals, normally iron. These furnaces trace their origin to China (around 500 BC). They were also found in Belgium and England later. They do not have any special mode of operation. The metals get melted by heating only. Generally, iron is melted in these furnaces. The chemical reaction can be explained as follows:

Fe2O3 + 3CO -> 2Fe + 3CO2

Bronze Metal Casting

Ann Knapp asked:


High pressure de-burring utilizes water jet streams from 3,000 to 7,500+ psi to knock unwanted burrs from finished parts. By processing cast, cut or bored parts through a high pressure system, companies are able to create high quality, consistently finished parts each time with no possibility of diminished effectiveness. High pressure de-burring operations though, do have limited applications.

Not all metal cutters leave the same types of burrs in the same location every time. In these cases of inconsistent burr removal, brushes and media tumblers are a better choice for the company. The following paragraphs outline some other de-burring options and explain why particular methods are suited for different applications.

Depending on a variety of factors such as casting condition, substrate thickness and cutting tool condition, unacceptable burrs can be left in parts. These can be removed via high pressure spray stream, power brushes, media in tumble units, or hydraulically controlled, probing brushes. Media and brushes can deliver acceptable results, but they do carry some negative characteristics.

Tumble de-burr systems require the parts to be unloaded and dropped into a media filled tumble unit. They are dumped, retrieved, and delivered to the next manufacturing stage via bins. If this process delivers satisfactory de-burring results for the manufacturer then the only thing left to do is to remove the media residue from the parts. In order to do that, a washer must be placed after the tumbler to sufficiently clean any soil created in the media tumbling process.

Although media tumbling units are relatively inexpensive, multiple part handling locations mean more operators are required to run the manufacturing cell. In addition, media residue must be washed off of the parts and a low pressure parts washer will be required to complete this task. In addition, this media tumbling assumes each part can handle rough part on part contact. Any part that cannot is not permitted to consider this method of de-burring parts.

Complex parts can contain intermittent and inconsistent burrs. Surface brushes used to de-burr extended rough faces are appropriate for these parts. An electrically energized brush is used to attack the part. This is an effective tool for cleaning parts that do not always have burrs in the same location. Brush wear in this process is tough to predict. The more the brush wears the less effective the de-burring becomes. This makes it critical to schedule brush replacement prior to reaching the level of acceptable finish. Although, this method relies upon diligent maintenance, this remains the ideal system for removing a wide range of burr sizes from an extended surface area.

Probing brushes are similar to surface brushes in their applications and limitations. These brushes are directed into the holes created by the tooling while the casting was bored. Like the surface brushes, probing brushes are most appropriate for parts that have inconsistent burr patterns. As is the case with surface brushes, these brushes are unpredictable in their wear and it is impossible to predict when they will need replacement.

The difficulty of knowing when to replace surface and probing brushes can give manufacturers headaches. Often, an inadequate brush is not detected until a customer complains to the manufacturer about unacceptable leftover burrs. Unfortunately for the company, by the time they receive the complaint from the customer; many shipments of unacceptable parts may have been shipped. Internal quality checks can help to schedule brush maintenance, but the time and labor involved with this maintenance can be prohibitive.

Methods of de-burring can be described through a simple analogy. Imagine the burrs as cans sitting atop a wall. Removing the burrs with a powered brush is analogous to removing the cans with a hand grenade. You will remove all the cans, but there is a possibility of damage to the wall itself. Removing burrs with tumbling media is like clearing a mountainside with a landslide. The rough patches are removed, but so is the beauty. The hydro system is a sharpshooter, knocking the burrs off with accuracy and leaving the wall, mountainside or part untouched.

Therefore, if a part has consistent placement of burrs, a high-pressure direct spray system is appropriate. An example of this can be found in an automotive transmission plant. An aluminum valve body, once milled, is left with a consistent roll over bore in the spool bore. A power brush cannot access the hole where the spur is located. A probing brush may be able to access the burr, but there is the chance that it will damage the machined surface of the part and render it scrap.

A high-pressure water stream can shoot into the hole and knock the bore off with precision. It can then flush the burr out, and do no damage to the machined surface. Assuming the burr is formed in the correct spot in the prior stages, the high-pressure water system will deliver the best quality possible every time.

Before committing to a hydro de-burring system, a company must make sure it will work for their part. If it does, then they must determine if the money they will make from delivering a high-quality end product is worth the cost of the machine.

Metal Casting Blog