Technology

Processo produttivo sinterizzati

The powder sinter process

Schema interattivo, per informazioni punta e clicca sui singoli macchinari
Interactive scheme, for information, point and click

Sbavatura/Burattatura

Questa operazione classificata come secondaria ha lo scopo, di rimuovere eventuali bave o ribeve derivate dalle operazioni precedenti, in alcuni casi queste ribeve, oltre che essere esteticamente sgradevoli, possono essere dannose per eventuali processi futuri.

Tumbling

This operation classified as secondary has the purpose of removing any burrs from previous operations, in some cases these burrs, as well as being aesthetically unpleasant, can be harmful for any future processes.

calibratura

Questa operazione ha lo scopo di aumentare la precisione del componente, infatti il particolare, viene introdotto con forza dentro uno stampo simile a quelli che lo ha generato, essendo il particolare poroso, è possibile applicargli una variazione di volume negativa (calibratura). I risultati principali di questa operazione sono, precisione anche dell’ordine dell’ IT6-IT5, superfici del componente estremamente lucide ed a bassa rugosità. Correzione degli errori dimensionali, dovuti a processi precedenti, difficilmente si possono correggere errori di posizione.

Coining

This operation has the aim of increasing the precision of the component, in fact the part is forced into a mold similar to those that generated it. Due to the fact that the part is porous, it is possible to apply a negative volume variation (calibration). The main results of this operation are, precision also of the order of IT6-IT5, extremely shiny and low-roughness component surfaces. Correction of dimensional errors due to previous processes but it is difficult to correct position errors.

Compattazione

In questa operazione, la miscela di polveri viene introdotta dentro lo stampo. Dopo la chiusura, i vari elementi dello stampo (punzoni matrici, anime, altro) iniziano a muoversi reciprocamente al fine di addensare la polvere, questa operazione termina con la fase di estrazione, in cui lo stampo si apre, e con opportuni movimenti, il pezzo compattato (che in gergo è detto al verde) viene delicatamente estratto dallo stampo. A questo punto, il componente ha raggiunto la densità specificata, e può essere manipolato ed inviato alle operazioni successive. Quando questa operazione avviene a temperature di circa 100-150°C superiori a quella ambiente (riscaldando opportunamente gli elementi dello stampo e la polvere stessa) l’operazione prende il nome di “compattazione a caldo”, ed il componente raggiunge densità più elevate che con la compattazione convenzionale, ne consegue un aumento progressivo di tutte le proprietà meccaniche

Compaction

In this operation, the powder mixture is introduced into the mold. After closing, the various elements of the mold (punches, dies, cores, other) begin to move reciprocally in order to compact the powder, this operation ends with the extraction phase, in which the mold opens, and with appropriate movements, the compacted piece (that is called green parts) is gently extracted from the mold. At this point, the component has reached the specified density, and can be manipulated and sent for subsequent operations. When this operation takes place at temperatures of about 100-150 ° C above the ambient one (by suitably heating the elements of the mold and the powder itself) the operation takes the name of "hot compaction", and the component reaches higher densities than with conventional compaction, the result is a progressive increase in all mechanical properties.

Impregnazione in fluidi od oli

Uno dei vantaggi indiscussi dei componenti sinterizzati, ed uno dei suoi più grandi punti deboli, è la presenza di una porosità residua del componente. E’ un vantaggio quando,ho necessità per esempio di realizzare un componente autolubrificante, la porosità può funzionare come serbatoio dell’olio lubrificante, e rilasciare questo in condizioni di utilizzo (Bronzine autolubrificanti sinterizzate). E’ uno svantaggio quando per esempio abbiamo la necessità di rendere impermeabile e sigillato il componente, in questo caso l’impregnazione avviene generalmente in resina che una volta polimerizzata, occupa, se è stata eseguita correttamente, tutti gli spazi lasciati vuoti dalla porosità all’interno del componente impedendo agli agenti esterni di penetrare nel componente.

Oil and Fluid impregnation

One of the undisputed advantages of sintered components, and one of its greatest weaknesses, is the presence of residual porosity of the component. It is an advantage when, for example, I need to make a self-lubricating component, the porosity can function as a lubricating oil reservoir, and release this in conditions of use (sintered self-lubricating bushings). It is a disadvantage when, for example, we need to make the component waterproof and sealed, in this case the impregnation generally takes place in resin which, once polymerized, occupies, if it has been done correctly, all the spaces left empty by the porosity preventing external agents from penetrating the component.

Lavorazione Meccanica

Il particolare sinterizzato come qualsiasi altro particolare di metallo, e non metallo, con opportuni parametri, può subire tutte le lavorazioni di asportazione di materiale degli acciai convenzionali, torniture, fresature, filettature ecc. Da sottolineare particolari lavorazioni che su componenti come ingranaggi hanno dato risultati sorprendenti in termini di aumento della resistenza a fatica, come la rullatura superficiale, e la pallinatura.

Machining

The sintered part like any other metal and not metal with suitable parameters can pass through all the material removal processes of conventional steels like turning, milling, threading, etc. To underline particular processes that on components such as gears have given surprising results in terms of increased fatigue resistance, such as surface rolling and shot peening.

miscelazione

Con questa operazione diversi elementi in forma di polvere che andranno a costituire il materiale del componente, vengono finemente ed omogeneamente mescolati, in modo che la loro concentrazione sia la più uniforme possibile.
In Molti casi vengono utilizzate miscele già formulate dal costruttore, in modo da avere le migliori garanzie di qualità.

Mixing

With this operation, various elements in the form of powder that will constitute the material of the component, are finely and homogeneously mixed, so that their concentration is as uniform as possible. In many cases, blends already formulated by the manufacturer are used, in order to have the best quality guarantees.

Ossidazione del Vapore Vaporizzazione

Questo trattamento è senza alcun dubbio uno dei più utilizzati ed applicati ai componenti sinterizzati. Consiste nel riscaldare il componente all’interno di un forno fino ad una temperatura compresa tra i 450-550°C, per poi far fluire i lambire i pezzi da una corrente di vapore surriscaldato alla medesima temperatura dei pezzi da trattare, A questa temperatura il Ferro Fe, si lega con l’ossigeno O2 presente nel vapore, formano il tetrossido di ferro cioè Fe3O4 (magnetite), questo rivestimento ossido conferisce al componente diverse proprietà:


  1. Essendosi formato ad una temperatura elevata, è un ossido stabile a alla temperatura ambiente quindi è un ottimo protettivo contro la ruggine
  2. Se il componente è stato eseguito con un materiale opportuno, questo ossido penetra all’interno del pezzo, e cresce all’interno della porosità chiudendola. Pezzo impermeabile specie ai gas.
  3. Conferisce un sensibile aumento della resistenza meccanica del componente, ma lo rende più fragile.
  4. Aumenta la resistenza ad usura del particolare, sia perché chiude le porosità, quindi la superficie tribologica è maggiore, sia perché l’ossido ha una durezza più elevata di quella del metallo base.
  5. E’ spesso utilizzato come base prima di eseguire altri trattamenti superficiali, sia galvanici che di riporto di vernici

Vaporization (Steam Oxidation)

This treatment is one of the most used and applied to sintered components. It consists in heating the component inside an oven up to a temperature between 450-550 ° C, and then letting the pieces flow by a stream of superheated steam at the same temperature as the pieces to be treated. Iron Fe, binds with the oxygen O2 present in the steam, forming the iron tetroxide i.e. Fe3O4 (magnetite), this oxide coating gives the component different properties:


  1. Having formed at a high temperature, it is a stable oxide at room temperature so it is an excellent protective against rust
  2. If the component was made with a suitable material, this oxide penetrates inside the piece, and grows inside the porosity, closing it. Piece impermeable especially to gases.
  3. It gives a significant increase in the mechanical resistance of the component, but makes it more fragile.
  4. The wear resistance of the part increases because closing the porosities the tribological surface is greater and because the oxide has a higher hardness than that of the base metal.
  5. It is often used as a base before performing other surface treatments, both galvanic and coatings of paints

Processi di giunzione

In Alcuni casi la forma del particolare, non consente la sua realizzazione in un unico componente stampato, ma sono necessari procedimenti di giunzione, tra i più efficaci troviamo:
  1. Assemblaggio forzato (può avvenire anche con componenti di diversa natura es. acciaio lavorato e sinterizzato).
  2. Unione in sinterizzazione o coosinterizzazione: i componenti da assemblare sono opportunamente posizionati ed accoppiati tra loro, prima della sinterizzazione cioè allo stato detto al verde.
  3. Sinterobrasatura . con l’aggiunta di additivi brasanti di varia forma e natura, più componenti sinterizzati, possono essere uniti sia durante che dopo la sinterizzazione, con altri componenti sinterizzati o di natura differente.
  4. Saldatura a proiezione ed ultrasuoni, sono le saladture più economiche e veloci, ed in molti casi le più efficaci.
  5. Altre saldature sono da considerarsi caso per caso.

Joining processes

In some cases the shape of the detail does not allow its realization in a single molded component, but joining procedures are necessary. The most effective are :
  1. Forced assembly (it can also take place with components of different nature like machined and sintered steel).
  2. Union in sintering or coosintering: the components to be assembled are suitably positioned and coupled together, before sintering (green state).
  3. Sinter-brazing with the addition of brazing additives of various shapes and nature, more sintered components can be joined both during and after sintering with other sintered components or of a different nature.
  4. Projection and Ultrasonic welding are the cheapest and fastest and in many cases the most effective.
  5. Other welds are to be considered case-by-case.

Ricompressione

Questa operazione è classificata come operazione secondaria, ma l suo scopo, è quello di aumentare la densità del componente compattato, raggiungendo nei materiali ferrosi, densità molto prossime a quelle teoriche. Dopo la ricompressione è infatti necessaria la “vera” sinterizzazione.

Post-compaction

This operation is classified as a secondary operation, but its purpose is to increase the density of the compacted component reaching , in ferrous materials, density very close to the theoretical ones . After recompression, "real" sintering is in fact necessary.

Rivestimenti superficiali

In generale si possono applicare a componenti sinterizzati gli stessi trattamenti superficiale dei componenti convenzionali, in particolare di particolare interesse ed applicazione troviamo:
  1. Trattamenti galvanici, come zincature , Cromatura . rivestimenti di Nikel, zinco, e stragno.
  2. Un Trattamento di particolare interesse che conferisce resistenze alla corrosione di comprovate prestazione è il DACROMET oggi sostituito dal GEOMET per compatibilità ambientali.
  3. Verniciatura a polvere, o liquida, o Cataforesi (necessario trattamento preliminare di vaporizzazione)

Surface Coatings

In general the same surface treatments as conventional components can be applied to sintered components. Of particular interest and application we find:
  1. Galvanic treatments, such as zinc plating, chromium plating. coatings of Nikel, zinc, and tin.
  2. DACROMET, now replaced by GEOMET for environmental compatibility is a treatment of particular interest which confers resistance to corrosion with proven performance.
  3. Powder or liquid painting or Cataphoresis (preliminary vaporization treatment required)

Sinterizzazione

In Questa operazione il pezzo compattato detto al verde, subisce un ciclo termico, composto da 3 fasi principali: Riscaldamento (che può avvenire anche con soste intermedie) sino alla temperatura di sinterizzazione, che dipende ovviamente dal materiale che si stà trattando e dalle caratteristiche che si vogliono ottenere. Permanenza per un determinato tempo alla temperatura di sinterizzazione, anche il questo caso il tempo di permanenza è una variabile che dipende dal materiale, ma è comunque meno influente della temperatura di permanenza. Raffreddamento fino alla temperatura ambiente. Una nota particolare và sottolineata, specificando che già da qualche anno per determinati componenti, si va affermando un trattamento di sinterizzazione particolare detto “sinterotempra”, il cui scopo, è quello di variabilizzare la velocità di raffreddamento dei componente, al fine di ottenere sugli acciaio, strutture di grano, Bainitiche, o martensitiche. Con questo processo, i particolari che devono essere trattati termicamente possono in alcuni casi, essere funzionali con questa operazione di sinterotempra. L’R.biemme, si è dotata negli ultimi anni di moderni forni che possono attuare in completa autonomia, ed sotto controllo di processo, questa operazione. Dopo l’operazione di sinterizzazione il particolare è pronto all’uso, a meno che non siano necessarie operazioni secondarie che di seguito descriveremo.

Sintering

In this operation, the compacted piece called green, receive a thermal cycle, consisting of 3 main phases: Heating (which can also take place with intermediate stops) up to the sintering temperature, which obviously depends on the material being treated and on the characteristics that you want to get. Reamining for a determined time at the sintering temperature, also in this case the permanence time is a variable that depends on the material, but is in any case less influential than the residence temperature. Cooling down to room temperature. A particular note should be emphasized, specifying that is some years for certain components that a particular sintering treatment called "sinter hardening" has been pulled out modifying cooling speed in order to obtain on the steel grain Bainitic or martensitic structures. With this process, the parts that need to be heat treated can in some cases be functional with this sinter tempering operation. In recent years, R.biemme has equipped itself with modern ovens that can carry out this operation in complete autonomy and under process control. After the sintering operation, the part is ready for use, unless secondary operations that could be required, which we will describe below.

Trattamenti termici

Come sugli acciai convenzionali anche sugli acciai sinterizzati, compatibilmente con il tenore di carbonio e le percentuali di elementi di lega, e possibile eseguire trattamenti generalmente conosciuti: tempra, carbo-cementazione, carbo-nitrurazione, tempra ad induzione, ecc. Particolari accorgimenti devono essere presi durante alcuni trattamenti, per effetto della porosità e compensare la maggior diffusione degli elementi presenti nell’atmosfera di protezione.

Heat Treatment

As on conventional steels, also on sintered steels, compatibly with the carbon content and the percentages of alloying elements, it is possible to carry out generally known treatments: hardening, carburizing, carbon nitriding, induction hardening, etc. Special precautions must be taken during some treatments, due to the porosity and so should be compensate the greater diffusion of the elements present in the protective atmosphere.

Materiali

Materiali a Base Alluminio
Materiali a Base Ferro
Materiali a Magneti Dolci
Materiali a Base Rame
Acciaio Inossidabile

Material

Material with aluminium base
Material with iron base
Material for soft magnetic
Material with copper base
Stainless Steel

Prodotti Finiti

Finished products

11 Apr

Technology

The powder sinter process is composed by the following steps:

– Material Selection: Material with aluminium base, Material with copper base, Material with iron base, stainless steel, Material for soft magnetic.

– Mixing: With this operation, various elements in the form of powder that will constitute the material of the component, are finely and homogeneously mixed, so that their concentration is as uniform as possible.
In many cases, blends already formulated by the manufacturer are used, in order to have the best quality guarantees.

– Compaction: In this operation, the powder mixture is introduced into the mold. After closing, the various elements of the mold (punches, dies, cores, other) begin to move reciprocally in order to compact the powder, this operation ends with the extraction phase, in which the mold opens, and with appropriate movements, the compacted piece (that is called green parts) is gently extracted from the mold. At this point, the component has reached the specified density, and can be manipulated and sent for subsequent operations. When this operation takes place at temperatures of about 100-150 ° C above the ambient one (by suitably heating the elements of the mold and the powder itself) the operation takes the name of “hot compaction”, and the component reaches higher densities than with conventional compaction, the result is a progressive increase in all mechanical properties.

– Sintering: In this operation, the compacted piece called green, receive a thermal cycle, consisting of 3 main phases: Heating (which can also take place with intermediate stops) up to the sintering temperature, which obviously depends on the material being treated and on the characteristics that you want to get. Reamining for a determined time at the sintering temperature, also in this case the permanence time is a variable that depends on the material, but is in any case less influential than the residence temperature. Cooling down to room temperature. A particular note should be emphasized, specifying that is some years for certain components that a particular sintering treatment called “sinter hardening” has been pulled out modifying cooling speed in order to obtain on the steel grain Bainitic or martensitic structures. With this process, the parts that need to be heat treated can in some cases be functional with this sinter tempering operation. In recent years, R.biemme has equipped itself with modern ovens that can carry out this operation in complete autonomy and under process control. After the sintering operation, the part is ready for use, unless secondary operations that could be required, which we will describe below.

– Tumbling: This operation classified as secondary has the purpose of removing any burrs from previous operations, in some cases these burrs, as well as being aesthetically unpleasant, can be harmful for any future processes.

– Coining: This operation has the aim of increasing the precision of the component, in fact the part is forced into a mold similar to those that generated it. Due to the fact that the part is porous, it is possible to apply a negative volume variation (calibration). The main results of this operation are, precision also of the order of IT6-IT5, extremely shiny and low-roughness component surfaces. Correction of dimensional errors due to previous processes but it is difficult to correct position errors. .

– Machining: The sintered part like any other metal and not metal with suitable parameters can pass through all the material removal processes of conventional steels like turning, milling, threading, etc… To underline particular processes that on components such as gears have given surprising results in terms of increased fatigue resistance, such as surface rolling and shot peening.

– Joining processes : Forced assembly , Union in sintering or coosintering , Sinter-brazing , Projection and Ultrasonic welding

– Heat Treatment: As on conventional steels, also on sintered steels, compatibly with the carbon content and the percentages of alloying elements, it is possible to carry out generally known treatments: hardening, carburizing, carbon nitriding, induction hardening, etc. Special precautions must be taken during some treatments, due to the porosity and so should be compensate the greater diffusion of the elements present in the protective atmosphere.

– Vaporization (Steam Oxidation): This treatment is one of the most used and applied to sintered components. It consists in heating the component inside an oven up to a temperature between 450-550 ° C, and then letting the pieces flow by a stream of superheated steam at the same temperature as the pieces to be treated. Iron Fe, binds with the oxygen O2 present in the steam, forming the iron tetroxide i.e. Fe3O4 (magnetite), this oxide coating gives the component different properties:

  1. Having formed at a high temperature, it is a stable oxide at room temperature so it is an excellent protective against rust
  2. If the component was made with a suitable material, this oxide penetrates inside the piece, and grows inside the porosity, closing it. Piece impermeable especially to gases.
  3. It gives a significant increase in the mechanical resistance of the component, but makes it more fragile.
  4. The wear resistance of the part increases because closing the porosities the tribological surface is greater and because the oxide has a higher hardness than that of the base metal.
  5. It is often used as a base before performing other surface treatments, both galvanic and coatings of paints.

– Oil and Fluid impregnation: One of the undisputed advantages of sintered components, and one of its greatest weaknesses, is the presence of residual porosity of the component. It is an advantage when, for example, I need to make a self-lubricating component, the porosity can function as a lubricating oil reservoir, and release this in conditions of use (sintered self-lubricating bushings). It is a disadvantage when, for example, we need to make the component waterproof and sealed, in this case the impregnation generally takes place in resin which, once polymerized, occupies, if it has been done correctly, all the spaces left empty by the porosity preventing external agents from penetrating the component.

– Surface Coating: In general the same surface treatments as conventional components can be applied to sintered components.
Of particular interest and application we find:

  1. Galvanic treatments, such as zinc plating, chromium plating. coatings of Nikel, zinc, and tin.
  2. DACROMET, now replaced by GEOMET for environmental compatibility is a treatment of particular interest which confers resistance to corrosion with proven performance.
  3. Powder or liquid painting or Cataphoresis (preliminary vaporization treatment required).

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