Turnarea în forme consumabile este un proces flexibil de fabricare a produselor metalice prin turnarea metalului topit în forme care sunt distruse după fiecare proces de producție. Forme consumabile. Spre deosebire de matrițele permanente, care pot fi regenerate, matrițele dispensabile sunt din material, cum ar fi nisip, ipsos sau ceramică, și sunt de unică folosință după realizarea turnării. Este modul potrivit de a fabrica piese cu forme complicate, precizie extremă și detalii minuscule care, cel mai probabil, nu erau simple sau fezabile cu alte procese. 

Industriile care necesită o producție de înaltă calitate în volume mici și medii pentru crearea de matrițe includ industria aerospațială, auto, medicală și de apărare și multe altele. Procesul poate fi nepotrivit în cazul producției pe scară largă, deoarece ar implica realizarea de noi matrițe pentru fabricarea fiecărei piese produse și, ca atare, s-ar dovedi costisitor, însă capacitatea sa de a fabrica modele complexe îl face neprețuit în cazul fabricării de articole care necesită rezistență, durabilitate și precizie.

Istoria turnării matrițelor consumabile

Turnare cu matrițe dispensabile are o istorie îndelungată și prezența sa poate fi urmărită încă de acum mii de ani. Printre civilizațiile care au utilizat acest proces pentru turnarea obiectelor se numără egiptenii, grecii și romanii, iar obiectele turnate includ bijuterii, monede și arme. Odată cu trecerea timpului, procesul s-a schimbat odată cu apariția de noi materiale și îmbunătățiri tehnologice care au permis o turnare mai complicată și mai precisă.

Apariția tehnicilor moderne de turnare a matrițelor consumabile poate fi urmărită până la revoluția industrială din secolele al XVIII-lea și al XIX-lea, când s-au înregistrat progrese intense în tehnologiile de prelucrare a metalelor. Odată cu apariția unor metode precum turnarea în nisip și turnarea în ceară pierdută, a devenit posibilă producerea de piese din metal într-un mod complet diferit, iar în prezent, utilizarea matrițelor de unică folosință în procesul de fabricație este un fapt evident. 

Ce este turnarea în matriță cheltuibilă?

Turnarea în matriță consumabilă poate fi definită ca un proces de fabricație care se aplică în producția de piese din metale, deoarece piesele fabricate sunt introduse într-o matriță care este concepută în mod deliberat pentru a fi distrusă după o singură utilizare. Comparativ cu turnarea în matriță permanentă, care permite reutilizarea matriței de mai multe ori, turnarea în matriță consumabilă implică matrițe reutilizabile. După ce metalul topit se răcește și se solidifică, modelul sau matrița este distrus pentru a obține produsul finit.

Acest procedeu este adecvat în special pentru turnarea pieselor complicate, care pot fi piese de înaltă precizie, care altfel ar fi costisitoare și chiar imposibil de realizat prin alte tehnici. Termenul "consumabil" înseamnă că matrița este consumată într-un singur ciclu, adică după fiecare utilizare trebuie dezvoltată o matriță nouă pentru a realiza o piesă diferită.

Cum se utilizează turnarea cu matrițe cheltuibile

Crearea modelului

În cazul turnării cu matrițe dispensabile, pasul inițial este realizarea unui model al piesei care urmează să fie turnată. Modelul este compus din materiale precum ceară, spumă sau metal și este configurat pentru a imita forma finală a produsului.

Formarea mucegaiului

Modelul este înconjurat de o substanță de turnare, care poate fi nisip, ipsos sau ceramică, iar materialul poate fi îndepărtat printr-o varietate de metode, în funcție de procesul de turnare utilizat.

Eliminarea modelului

Odată ce materialul matriței se întărește, modelul este scos și de cele mai multe ori acest lucru se face prin topire, ardere sau spargere. Acest lucru formează o gaură goală în matriță care are forma exactă a modelului original.

Turnarea metalului

După ce cavitatea matriței a fost pregătită, se introduce metal topit în matriță, care umple cavitatea lăsată de model. Metalul se răcește și se face să se solidifice.

Distrugerea mucegaiului

Odată ce metalul s-a răcit și s-a solidificat, matrița este distrusă (de obicei prin spargere și zdrobire sau dizolvare) pentru a recupera turnarea.

Post-procesare

Odată ce turnarea a fost scoasă din matriță, aceasta poate fi rafinată în continuare prin tehnici secundare de finisare, cum ar fi procesele de prelucrare sau lustruire, pentru a obține specificațiile necesare.

Tipuri de turnare a matrițelor consumabile

Haideți să aprofundăm puțin tipul de turnare a matrițelor dispensabile:

1. Turnarea în nisip

Turnarea cu matrițe dispensabile. Una dintre cele mai comune metode de turnare în nisip este turnarea în nisip. Aceasta necesită realizarea unei matrițe, care se face prin împachetarea nisipului, care este de obicei amestecat cu un amestec de argilă și apă, în jurul unui model (modelul a ceea ce urmează să fie turnat). În general, se utilizează un model de metal sau de ceară, iar după ce matrița s-a solidificat, modelul este spart sau topit.

Prezentare generală a procesului:

• Un material, cum ar fi metalul sau ceara, este realizat sub forma unui model.
• Amestecul de nisip, argilă și apă este apoi acoperit în jurul modelului.
• Modelul este respins, iar întărirea nisipului are loc prin încălzirea matriței.
• Cavitatea lăsată de model este umplută cu metal topit care este turnat.
• După ce metalul s-a solidificat, matrița este spartă pentru a expune piesa turnată.

Avantaje:

• Funcționează eficient din punct de vedere al costurilor atunci când volumul de producție este scăzut sau mediu.
• Capacitatea de a produce piese turnate în vrac având o geometrie simplă.
• Multifuncțional, poate fi fabricat din diferite materiale, aluminiu, fier și oțel.
• Foarte răspândită în industria auto, industria grea și cea a utilajelor.

Dezavantaje:

• Finisajul suprafeței nu este la fel de neted ca celelalte metode de turnare.
• Modelele foarte fine nu funcționează bine.

2. Turnare de investiții (turnare în ceară pierdută)

O altă metodă foarte precisă de turnare a matrițelor consumabile este turnarea prin investiții, cunoscută și sub denumirea de turnare cu ceară pierdută. Acesta este un proces de aplicare a unui model de ceară cu un înveliș ceramic care se usucă pentru a se întări. Ceara este apoi topită și scursă, lăsând o matriță ceramică goală în care se toarnă metal topit.

Prezentare generală a procesului:

• Modelul de ceară este format de un model care este turnat în designul preferat.
• Pentru a obține o coajă groasă, modelul de ceară este acoperit cu un strat de această suspensie, apoi cu nisip.
• Toată matrița este apoi încălzită, iar ceara topită este golită.
• Învelișul ceramic este apoi metal topit.
• După ce metalul a avut timp să se solidifice, învelișul ceramic se rupe pentru a arăta mulajul.

Avantaje:

• Astfel de calități de precizie ridicată și finisaje de suprafață foarte bune.
• Cel mai bun atunci când este folosit pentru turnarea detaliilor mici și a pieselor complexe.
• Acesta poate fi aplicat unui spectru foarte larg de metale, cum ar fi oțelul inoxidabil, titanul și metalele prețioase.

Dezavantaje:

• Condițiile speciale sunt mai scumpe decât turnarea în nisip.
• Este mai consumatoare de timp.
• Adecvat pentru serii mici de fabricație a componentelor, neadecvat pentru producția care implică fabricarea în serie.

3. Shell Moulding

Shell molding Shell molding is also a casting process that is closely related to investment casting in principle, however, the pattern is now a sand based shell around a pattern made of metal. The process is also credited with high accuracy of dimensioning parts as well as smooth surface finishes of parts.

Prezentare generală a procesului:

• A metal pattern is tempered and submerged in fine sand slurry.
• The pattern sets in the sand, forming the shell.
• When the shell is ready the shell is then heated until only any remaining pattern material is to be found.
• The shell filled with molten metal is poured, and when the metal solidifies, the shell is broken in order to remove the casting.

Avantaje:

• Manufactures pieces that are of superb dimensional accuracy and ironed edges.
• It is appropriate for casting complicated parts.
• Can work on metals with a high melting point, such as steel and iron.

Dezavantaje:

• It is more expensive compared to sand casting.
• Since it takes a lot of time to create a precise shell, they are limited to smaller pieces.
• It is not as diverse with regard to the choice of material as sand casting.

4. Lost Foam Casting (LFC )

Lost Foam Casting (LFC) Lost Foam Casting is a new form of expendable mould casting utilising foam patterns instead of metal or wax patterns. The foam pattern is covered in sand and melted metal poured into the hole, blurring the use of foam.

Prezentare generală a procesului:

•  A foam mould of the piece which is to be cast is made.
• A layer of sand is then applied to the pattern of the foam, and the sand is pressed to make a mould.
• Heating of the mould is done, and molten metal is poured into it.
• The pattern covered with foam is vaporised by the molten metal, and the remainder is the solidified section.

Avantaje:

• It is perfect for casting complex Geometries with low work destroyed.
• It is capable of producing high detail and amazingly smooth parts.
• Affordable for low and medium volume.

Dezavantaje:

• It is restricted to small pieces.
• Expensive moulds as opposed to the conventional sand casting.
• It does not apply to all kinds of metals because the temperature and pressure should be adjusted carefully.

5. Casting Moulding of Plaster

Plaster mold casting incorporates the process of molding a plaster. The plaster is combined with water then applied on a pattern usually afterwards the pattern is removed when it hardens. It is mostly applied to small parts with details.

Prezentare generală a procesului:

• A template is made either of metal or some related substance.
• The pattern is plunged in a solution of plaster, water and other materials to produce a mould.
• The mould is afterwards hardened and heated to cast out the reticulate.
• The casting production takes place by pouring molten metals into the mould.

Avantaje:

• Manufactures good quality parts with a good surface finish.
• Applicable to small parts as well as parts characterised by fine details.
• It is applicable in low-volume production.

Dezavantaje:

• Methods such as these are expensive and time-consuming.
• Restricted to smaller components and metals that melt at a low temperature.

6. Permanent Pattern- Sand Casting

This is a reusable approach (using a reusable pattern, as opposed to an expendable pattern) though the reusable pattern is a disposable mold. It is a combination method wherein the mold is recycled pattern but the sand mold is demolished after every casting.

Prezentare generală a procesului:

• A mould box is made with a permanent pattern within it and sand packed around.
• After having made the sand mould, the pattern is carried off, and molten metal is poured into the cavity.
• The casting process destroys the sand to remove the final product.

Avantaje:

• During low- to medium-volume production, it is more cost-effective than injection moulding.
• It is suitable for bigger parts such as engine blocks and frames.

Dezavantaje:

• Little precision and surface finish when put next to investment casting.

7. CGP or Cold Box Process

Chemically bonded sand castings from chemically bonded sand moulds are cast using the cold box process. The sand is combined with a binding agent, and the moulding set is used without heating. This is mostly in the manufacture of parts of industries that need durability and toughness, like oil and gas.

Prezentare generală a procesului:

• The mould is made out of sand combined with a chemical binder and compacted.
• Once in the mould, it is cured in a cold environment, and the mould hardens without the need to use heat.
• There is the pouring of molten metal into the mould, after which it is allowed to solidify then the mould is removed.

Avantaje:

• It is applicable where a high level of strength is needed in the parts that are being cast.
• Ideal castings: suitable for metals that could be hard to cast in the normal sand moulds.

Dezavantaje:

• Chemical binders that are necessary in the process of mould making might not fit all metals.
• It is restricted to materials and applications.

Materials applied in expendable mould casting

In expendable mould casting, the mould is to be constructed out of material that is designed to be destroyed after one use. The material used is also determined by the process used to cast, the material to cast, and the needs of a particular part. Some of the frequently used materials in expendable mould casting are given below:

1. Sand

Expendable moulds made of sand are most often used and most commonly in sand casting. It is combined with some kind of binder (e.g. clay or resin) and cast in a mould capable of resisting the heat of molten metal. Sand moulds are flexible, economical, and can be used to make large components.

2. Plaster

With plaster mould casting, moulds are made using a mixture of gypsum plaster and water. The material can be used to cast small, high-detail pieces where smooth surfaces and fine detail are required. The plaster moulds are usually employed to produce non-ferrous metals in lower volumes.

3. Ceramic

Investment casting (lost wax castings) and shell moulding utilise ceramic materials. A pattern is covered with a fine ceramic slip, and after drying, a rigid mould is created that is suitable to resist the high temperature. Casting of steels, titanium, and high-performance alloys is undertaken by the use of ceramic moulds.

4. Wax

Wax is mainly utilised in investment casting (lost wax casting). It is made in wax, and a ceramic shell is added on. The only shell you will be left with after removing the pattern by melting is the shell in which casting is done. Wax will be ideal to make very detailed and intricate parts.

5. Foam

In the lost foam casting, foam acts as the pattern material. The foam pattern is covered with sand, and upon pouring molten metal into it, the foam vaporises, leaving the solidified molten metal casting. The foam moulds are also advantageous in the casting of complicated geometrical designs with reduced waste.

6. Resin

In other advanced casting techniques, resin materials are applied to form moulds,s which are highly accurate and sturdy. Cold box and shell moulding generally occurs by using resin-bonded sand. Resins may also be useful to give a good surface finish and detailed casting in the final casting.

7. Metal Alloys (for having patterns)

In some expendable molds casting systems such as metal pattern sand casting, the pattern is made out of metal alloys. The molds are then cast and molten metal poured and these metal patterns are drawn off later.

Advantages OF Expendable Mould Casting

Expendable mould casting has a number of advantages, enabling it the choice of many applications. Among these benefits, there are:

1. Complex-Shape Casting ability

Expendable moulding casting techniques (e.g. investment casting and lost foam casting) have the potential to produce parts with complex designs that could ,not be produced using alternative manufacturing such as machining or stamping. This qualifies it to be used in industries where complicated parts are needed, and these are the aerospace and automotive industries.

2. Surface Finish and High Precision

Some techniques such as investment casting and shell molding result in great surface finishes and small details on the part. This allows fewer extra machining and finishing processes resulting in it being cheaper in certain working cases.

3. Material Versatility

Expendable mold casting has a very broad latitude in the variety of materials that may be used and these can include metals like aluminum, steel and titanium to more exotic alloys. This adaptability is what qualifies it to be used in many industries including automotive and medical.

4. Short Lead Time

The molds in the expendable mold casting process are disposable hence the preparation of the molds and the castings may relatively take less time unlike other casting processes that use reusable molds. The result is that expendable mold casting is suitable on low to medium-volume production runs.

5. Small Run Cost-effective

The capital needed to install expendable mold casting technologies such as investment casting can be quite high but the price per part is reduced substantially in cases where small and medium-sized production runs are required. This comes in handy especially in industries that require small quantities of highly precise parts but do not want to spring up the cost of large scale production.

Problems of the Expendable Mould Casting

Though there are abundant benefits of the method, expendable mould casting has its share of challenges as well:

1. Mould Destruction

This may cause high cost of high-volume production runs because the mold is ruined after one casting. New molds have to be made each time the casting comes down and this may be an expensive process making expendable mold casting less attractive on mass productions.

2. Mould reusability is restricted

With a permanent mold casting, the molds are re-usable and may be re-used many times, in contrast, the molds used in the expendable mold casting are required to be reproduced with each new piece. This raises costs used in terms of material and labor involved in the process.

3. Smaller Run Production

Expendable mold Really, as production runs are smaller, expendable molds casting is sometimes better depending on how expensive and time-consuming it is to cast a new mold. Other techniques such as die casting or permanent mold casting are more affordable on high-volume production.

Expendable Mould Casting Uses

The expendable mould casting is used in so many industries where complex geometries in high-precision parts are necessary. One of the major uses can be outlined as:

1. Industria aerospațială

Examples of items manufactured in the aerospace industry by expendable mould casting are turbo-shear blades, housings, and other components where high strength, accuracy and material abilities to withstand severe temperatures are required. The investment casting finds especially ,favour in this industry because it can produce complicated shapes, tending towards superior surface finishes.

2. Industria auto

Automotive industry depends upon expendable mold casting to make components like engine blocks, transmission housings and other components which are required to be strong and durable. This sector normally uses sand casting and shell molding.

3. Manufacturing of Medical Devices

Medical equipment including surgical equipment, implant and prosthetics are produced using expendable mold casting. This is most suitable in the medical field as their fit and functionality are of great essence and the complexity in the parts can be easily provided by this technology.

4. Military and Defence

On the defense end, expendable mold casting is utilized in the manufacture of the weapons, armor and other military equipment parts. In this industry, performance and reliability are important factors, the capacity to construct complex and robust components is critical.

GC Precision Mould: A Company that You Can Rely On

GC PrecisionMould is a company that produces quality and accurate moulding for different industries. We also offer custom mould designing, custom mould manufacturing, and custom moulds delivered with high levels of precision and strength. Our state-of-the-art technologies and the latest methods guarantee that every mould is up to the utmost standards of performance and efficiency. Call on GC Precision Mould to satisfy your need for elaborate geometries and the sharpest details. GC Precision Mould provides professional service in mould casting, including expendable and permanent mould casting. We at our team are ready to provide timely, economical solutions that suit the needs of each of our clients.

Concluzie

Expendable mould casting is a variable and necessary manufacturing procedure that has gone the distance. This method enables the production of parts, which have complex shapes, precision, as well as excellent surface finishes, by utilising liners made of a disposable material in the moulds. Although it might not be ideal in applications that require large volumes in production, its capability to produce complex parts as well as customised parts makes it invaluable in industries like the aerospace, auto, medical, and defence industries.

With advancing technology, there is more likely to be more ways and means of expendable mould casting, and this process would only become all the more significant in the sphere of manufacturing. Be it a miniature medical device or a huge aerospace part, the expendable mould casting has what it takes in flexibility, precision and material versatility to keep up with the challenges in modern industries.

Questions that are frequently, askedd 

1. What is the greatest benefit of using expendable mould casting?

Moulds are cast using expendable mould patterns so that parts with a complex pattern can be created with high precision. After every casting, the mould has to be destroyed, so hence, it is ideal for making detailed shapes and employing a wide range of materials.

2. What is the time of expendable mould casting?

Depending on the complexity and other factors, such as the mould type used, it could take a few hours or several days.

3. Is expendable mould casting applicable in large-scale production?

The expendable mould casting process is not most suited for large volumes of production because new moulds need to be created every time each of the parts is produproducedich is quite expensive on a large production scale.