Cold isostatic pressing - Revision history

M.bram: /* General principle of cold isostatic pressing (CIP) */

2021-08-04T11:45:43Z

‎General principle of cold isostatic pressing (CIP)

M.bram: /* How to conduct a cold isostatic pressing cycle */

2021-08-04T11:44:18Z

‎How to conduct a cold isostatic pressing cycle

M.bram: /* General principle of cold isostatic pressing (CIP) */

2021-08-04T11:30:50Z

‎General principle of cold isostatic pressing (CIP)

M.bram: /* How to conduct a cold isostatic pressing cycle */

2021-08-04T11:30:10Z

‎How to conduct a cold isostatic pressing cycle

M.bram: /* How to conduct a cold isostatic pressing cycle */

2021-08-04T11:29:08Z

‎How to conduct a cold isostatic pressing cycle

M.bram: /* General principle of cold isostatic pressing (CIP) */

2021-08-04T11:25:41Z

‎General principle of cold isostatic pressing (CIP)

M.bram: /* Applications of cold isostatic pressing */

2021-08-04T11:24:17Z

‎Applications of cold isostatic pressing

M.bram at 11:23, 4 August 2021

2021-08-04T11:23:09Z

M.bram: /* How to conduct a cold isostatic pressing cycle */

2021-08-04T08:34:24Z

‎How to conduct a cold isostatic pressing cycle

M.bram: /* How to conduct a cold isostatic pressing cycle */

2021-08-04T08:32:02Z

‎How to conduct a cold isostatic pressing cycle

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 == General principle of cold isostatic pressing (CIP) ==
-The cold isostatic pressing CIP is based on the effect that a pressure applied to a liquid spreads evenly in all directions (so-called Pascal's principle). Inside the liquid, this leads to a homogeneous pressure distribution, which can be used for shaping ceramic and metallic powders if the powder is encapsulated in an elastic die. Elastic polymers (elastomers) such as polyurethane (PU), polyvinyl chloride (PVC), synthetic or natural rubber have proven successful as materials for the elastic die. The main components of a cold isostatic press are the recipient filled with the pressure transmission medium, the high-pressure pump, the locking system, the overpressure protection and the system control. The recipient is a pressure cylinder, which consists of either a high-strength, thick-walled steel cylinder or a thin-walled steel vessel with a pre-tensioned wire winding. '''Figure 1''' shows a cold isostatic press in lab scale.
+The cold isostatic pressing (CIP) is based on the effect that a pressure applied to a liquid spreads evenly in all directions (so-called Pascal's principle). Inside the liquid, this leads to a homogeneous pressure distribution, which can be used for shaping ceramic and metallic powders if the powder is encapsulated in an elastic die. Elastic polymers (elastomers) such as polyurethane (PU), polyvinyl chloride (PVC), synthetic or natural rubber have proven successful as materials for the elastic die. The main components of a cold isostatic press are the recipient filled with the pressure transmission medium, the high-pressure pump, the locking system, the overpressure protection and the system control. The recipient is a pressure cylinder, which consists of either a high-strength, thick-walled steel cylinder or a thin-walled steel vessel with a pre-tensioned wire winding. '''Figure 1''' shows a cold isostatic press in lab scale.
 The pressure transmission media used are preferably water with the addition of an anti-corrosion agent, oil-water emulsions or glycerine. A hydraulic unit like an axial piston pump is used to build up pressure. This unit is connected to the recipient via a fluid transport system with appropriate valves and throttles. The pressure cylinder is sealed, for example, by a polymer O-ring that is integrated into the cover plate and is pressed into a groove when the pressure is built up. In order to absorb the large forces in the axial direction, the cover plate of the recipient is usually supported by a massive yoke. A rupture disc is used to protect against overpressure, which fails when the critical pressure is exceeded and thus enables a regulated pressure release before irreversible damage to the recipient occurs. Cold isostatic pressing is carried out in most cases at room temperature. In specially designed presses, moderate heating of the pressure medium up to a maximum temperature of 300 °C is possible.

@@ Line 70: / Line 70: @@
 The decompression at the laboratory facility of the IEK-1 institute (type CIP 400-125 * 300Y, EPSI, Belgium) is initiated by opening a pneumatic high-pressure valve. The pressure release can then be regulated either manually via a valve or via an adjustable throttle valve. The throttle valve consists of a high pressure tube in which a needle is inserted. The decompression speed is controlled by the inner diameter of the tube and the position and thickness of the needle. '''Figure 7''' shows the display for initiating decompression and the throttle valve, which is located on the rear of the cold isostatic press.
-[[File:Wiki Keramik KIP Abb 07.jpg|thumb|center]]
+[[File:Wiki Keramik KIP Abb 07 englisch.jpg|thumb|center]]
 '''Figure 7:''' ''a.) Display for selecting the decompression mode b.) Throttle valve.''

@@ Line 14: / Line 14: @@
 [[File:Wiki Keramik KIP Abb 01.jpg|thumb|center]]
-'''Figure 1:''' Cold isostatic press on a laboratory scale operated at the institute IEK-1, Forschungszentrum Jülich (manufacturer EPSI, type CIP 400-125 * 300Y). Usable volume: Diameter 125 mm, height = 300 mm.<br>
+'''Figure 1:''' ''Cold isostatic press on a laboratory scale operated at the institute IEK-1, Forschungszentrum Jülich (manufacturer EPSI, type CIP 400-125 * 300Y). Usable volume: Diameter 125 mm, height = 300 mm.''<br>
 == Advantages and limitations of cold isostatic pressing ==

@@ Line 27: / Line 27: @@
 Type:				CIP 400-125*300Y<br>
-Manufacturer:			EPSI, Temse, Belgien<br>
+Manufacturer:			EPSI, Temse, Belgium<br>
 Material of recipient:		SA 723 Class 3<br>
 Recipient inner diameter:	125 mm<br>
 Recipient inner height:		300 mm<br>
-Maximum sample size:		limited by recipient volume<br>
+Maximum sample size:		Limited by recipient volume<br>
 Maximum filling height:		295 mm<br>
 Recipient volume:		3.7 Liter<br>

@@ Line 26: / Line 26: @@
 In the following, it is explained in detail which processing steps are carried out in cold isostatic pressing and what must be considered in order to obtain crack-free samples and avoid damage to the system. The processing steps shown were carried out in a cold isostatic laboratory press of the following type:
-Type:				CIP 400-125*300Y
+Type:				CIP 400-125*300Y<br>
-Manufacturer:			EPSI, Temse, Belgien
+Manufacturer:			EPSI, Temse, Belgien<br>
-Material of recipient		SA 723 Class 3
+Material of recipient:		SA 723 Class 3<br>
-Recipient inner diameter:	125 mm
+Recipient inner diameter:	125 mm<br>
-Recipient inner height:		300 mm
+Recipient inner height:		300 mm<br>
-Maximum sample size:		limited by recipient volume
+Maximum sample size:		limited by recipient volume<br>
-Maximum filling height:		295 mm
+Maximum filling height:		295 mm<br>
-Recipient volume:		3.7 Liter
+Recipient volume:		3.7 Liter<br>
-Nominal operating pressure:	4000 bar (400 MPa)
+Nominal operating pressure:	4000 bar (400 MPa)<br>
-Maximum operating pressure:	4400 bar (440 MPa)
+Maximum operating pressure:	4400 bar (440 MPa)<br>
-Safety factor:			1,1 (related to 4840 bar, 484 MPa)
+Safety factor:			1,1 (related to 4840 bar, 484 MPa)<br>
-i.) '''Encapsulation of the samples:''' Even with cold isostatic pressing, a uniform filling of the mold and a high filling density are basic requirements for successful compaction of the powder. In order to estimate the flowability of the powder, it is recommended to measure the bulk and tap density in accordance with DIN ISO 3923 and DIN ISO 3953. The flowability of a powder can be improved by granulating in a fluidizing bed or by spray drying. During granulation, spherical, easily flowable agglomerates are formed, which have a relatively low stability and are destroyed during the cold isostatic pressing. Some powder manufacturers offer powder directly in a granulated state. In order to increase the bulk density in the mold, the elastic die can optionally be vibrated or subjected to ultrasonic treatment. As an example, Figure 2 shows a simple elastic mold made of rubber for cold isostatic pressing of round bars.
+i.) '''Encapsulation of the samples:''' Even with cold isostatic pressing, a uniform filling of the mold and a high filling density are basic requirements for successful compaction of the powder. In order to estimate the flowability of the powder, it is recommended to measure the bulk and tap density in accordance with DIN ISO 3923 and DIN ISO 3953. The flowability of a powder can be improved by granulating in a fluidizing bed or by spray drying. During granulation, spherical, easily flowable agglomerates are formed, which have a relatively low stability and are destroyed during the cold isostatic pressing. Some powder manufacturers offer powder directly in a granulated state. In order to increase the bulk density in the mold, the elastic die can optionally be vibrated or subjected to ultrasonic treatment. As an example, '''Figure 2''' shows a simple elastic mold made of rubber for cold isostatic pressing of round bars.
 [[File:Wiki Keramik KIP Abb 02.jpg|thumb|center]]
@@ Line 44: / Line 44: @@
 ''<br>
-As mentioned above, there is also the possibility of post-compaction of uniaxially pressed semi-finished parts using cold isostatic pressing. Figure 3 shows how the welding of a pre-pressed part into an elastic foil can be carried out. For this purpose, at the IEK-1 institute, a vacuum sealer is used, which is usually applied in the household for sealing and freezing food. Elastic foils, which are established for this purpose, are suitable for encapsulation of pre-pressed parts in cold isostatic pressing as well. The sample is placed in the prepared bag, then interior is evacuated and the bag is finally liquid-tight welded. A more primitive alternative is to put the sample in a latex glove, which is evacuated, for example, by a water jet pump and sealed with a string.
+As mentioned above, there is also the possibility of post-compaction of uniaxially pressed semi-finished parts using cold isostatic pressing. '''Figure 3''' shows how the welding of a pre-pressed part into an elastic foil can be carried out. For this purpose, at the IEK-1 institute, a vacuum sealer is used, which is usually applied in the household for sealing and freezing food. Elastic foils, which are established for this purpose, are suitable for encapsulation of pre-pressed parts in cold isostatic pressing as well. The sample is placed in the prepared bag, then interior is evacuated and the bag is finally liquid-tight welded. A more primitive alternative is to put the sample in a latex glove, which is evacuated, for example, by a water jet pump and sealed with a string.
 [[File:Wiki Keramik KIP Abb 03.jpg|thumb|center]]
 '''Figure 3:''' ''Sealing of a uniaxially pre-pressed sample in an elastic foil using a household vacuum sealer a.) Insertion of the uniaxially pre-pressed sample b.) Evacuation c.) Liquid-tight sealed sample.''
-ii.) '''Opening the recipient:''' Figure 4 shows the individual steps for opening the recipient of the cold isostatic press of the type CIP 400-125 * 300Y (EPSI, Belgium). The press is equipped with a hydraulic lifting device. A screw is attached to this, via which the cover plate is connected to the hydraulic lifting device. The screw is protected from damage by a cage. After the screw has been attached, the cover is lifted using the lifting device. The sealing ring can be seen on the lower edge of the cover plate. This ring is pressed into the groove when the pressure is built up.
+ii.) '''Opening the recipient:''' '''Figure 4''' shows the individual steps for opening the recipient of the cold isostatic press of the type CIP 400-125 * 300Y (EPSI, Belgium). The press is equipped with a hydraulic lifting device. A screw is attached to this, via which the cover plate is connected to the hydraulic lifting device. The screw is protected from damage by a cage. After the screw has been attached, the cover is lifted using the lifting device. The sealing ring can be seen on the lower edge of the cover plate. This ring is pressed into the groove when the pressure is built up.
 iii.) '''Introducing the sample into the recipient:''' For safety reasons it is important that the welded sample is not positioned directly in the oil-water emulsion. In the worst case, the sample or parts of the elastic foil can get into the liquid transport system of the cold isostatic press and block it, so that a pressure reduction is no longer possible and a service technician has to be called in. To safely avoid this risk, the sample must be placed in the oil-water emulsion in a specifically designed metal cage shown in Figure 4f. Spacers are welded onto the underpart of the metal cage, which prevent the metal mesh from resting directly on the bottom of the recipient. In this way, an unhindered pressure build-up and release is ensured. The metal cage also makes it easier to remove the sample after the cycle from the oil-water emulsion.
@@ Line 56: / Line 56: @@
 '''Figure 4:''' ''Preparation of the system for the CIP cycle a.) Closed system b.) Attaching the screw to the cover plate c.) Starting the opening process d.) Open system e.) View on the oil-water emulsion f.) Metal cage for placing the encapsulated sample in the CIP device.''
-iv.) '''Closing the recipient:''' After installing the metal cage including the sample in the recipient, the cover plate is closed via the hydraulic lifting system and the screw for fixing the cover plate is removed. The yoke, which absorbs the pressure in the axial direction, is then positioned over the cover plate. A specially designed locking system guarantees the exact position of the yoke in relation to the recipient. The locking bar is manually locked in the pressing position with a lever. Figure 5 shows the individual steps for closing the recipient.
+iv.) '''Closing the recipient:''' After installing the metal cage including the sample in the recipient, the cover plate is closed via the hydraulic lifting system and the screw for fixing the cover plate is removed. The yoke, which absorbs the pressure in the axial direction, is then positioned over the cover plate. A specially designed locking system guarantees the exact position of the yoke in relation to the recipient. The locking bar is manually locked in the pressing position with a lever. '''Figure 5''' shows the individual steps for closing the recipient.
 [[File:Wiki Keramik KIP Abb 05.jpg|thumb|center]]
 '''Figure 5:''' ''a., b.) Closing the recipient using the hydraulic lifting device c.) Locking the yoke before starting the pressing cycle.''
-v.) '''Pressure build-up and dwell time, protection against overpressure:''' As mentioned at the beginning, the pressure build-up takes place by a high-pressure pump which is connected to the interior of the recipient via the liquid transport system. Figure 6 shows the system components relevant for pressure build-up. The desired pressure and the dwell time at this pressure are programmed via the system control display. The pressure is applied at the speed as defined in the program. The run of the pressure curve and the actual pressure can be read directly on the display and on an analog manometer. The cold isostatic press operated on the IEK-1 is designed for a maximum pressure of 4400 bar (440 MPa). To be on the safe side, the pressure in standard operation of the system should not exceed 4000 bar (400 MPa). The system is equipped with a rupture disc as overpressure protection. The rupture disc protects the system from uncontrolled failure and is designed with a safety factor of 1.1 based on the maximum pressure.
+v.) '''Pressure build-up and dwell time, protection against overpressure:''' As mentioned at the beginning, the pressure build-up takes place by a high-pressure pump which is connected to the interior of the recipient via the liquid transport system. '''Figure 6''' shows the system components relevant for pressure build-up. The desired pressure and the dwell time at this pressure are programmed via the system control display. The pressure is applied at the speed as defined in the program. The run of the pressure curve and the actual pressure can be read directly on the display and on an analog manometer. The cold isostatic press operated on the IEK-1 is designed for a maximum pressure of 4400 bar (440 MPa). To be on the safe side, the pressure in standard operation of the system should not exceed 4000 bar (400 MPa). The system is equipped with a rupture disc as overpressure protection. The rupture disc protects the system from uncontrolled failure and is designed with a safety factor of 1.1 based on the maximum pressure.
 [[File:Wiki Keramik KIP Abb 06.jpg|thumb|center]]
@@ Line 68: / Line 68: @@
 vi.) '''Decompression:''' Decompression is the most critical step in cold isostatic pressing. If there is still air in the sample after the sample preparation, it is strongly compressed during the CIP cycle. The high compression of the powder compact is associated with a strong reduction in the residual porosity. Accordingly, after pressing, there is a high flow resistance for the compressed air to escape and the pressure release takes a certain amount of time (up to a few minutes, depending on the pressing density achieved). If the pressure is released suddenly, this can lead to failure of the compact by severe cracking. It should be noted that a powder compact is also deformed elastically in addition to plastic deformation. When the pressure is released, there is therefore an elastic rebound of the pressed part ("spring-back" effect), which can be between 0.5 - 2%. Since the compression takes place in an elastic mold, the spring-back is viewed as less critical, but in the worst case it can also lead to damage to the pressed part, e.g. if it sticks to the die wall.
-The decompression at the laboratory facility of the IEK-1 institute (type CIP 400-125 * 300Y, EPSI, Belgium) is initiated by opening a pneumatic high-pressure valve. The pressure release can then be regulated either manually via a valve or via an adjustable throttle valve. The throttle valve consists of a high pressure tube in which a needle is inserted. The decompression speed is controlled by the inner diameter of the tube and the position and thickness of the needle. Figure 7 shows the display for initiating decompression and the throttle valve, which is located on the rear of the cold isostatic press.
+The decompression at the laboratory facility of the IEK-1 institute (type CIP 400-125 * 300Y, EPSI, Belgium) is initiated by opening a pneumatic high-pressure valve. The pressure release can then be regulated either manually via a valve or via an adjustable throttle valve. The throttle valve consists of a high pressure tube in which a needle is inserted. The decompression speed is controlled by the inner diameter of the tube and the position and thickness of the needle. '''Figure 7''' shows the display for initiating decompression and the throttle valve, which is located on the rear of the cold isostatic press.
 [[File:Wiki Keramik KIP Abb 07.jpg|thumb|center]]

← Older revision		Revision as of 11:24, 4 August 2021
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	== Applications of cold isostatic pressing ==		== Applications of cold isostatic pressing ==
		+
		+	Cold isostatic pressing is widely used in industry as well as in research and development. One advantage is the great flexibility of the method and the comparatively low costs for the die production. Cold isostatic pressing can be used universally for the compression of oxides, nitrides, borides, graphite, hard metals and other composite materials, as well as for metallic powders. The starting powder should have good compressibility, since the use of high proportions of binder is rather unusual with this method. In general, this method is used to manufacture semi-finished products as well as structural and functional components with moderate geometrical complexity. Specific application examples are spark plug insulators made of alumina, cap insulators, components for lambda sensors, semi-finished products for ceramic insulators and semi-finished products for ceramic balls. Metallic filter cartridges with a length of up to 1.8 m and a diameter of up to 300 mm are also manufactured using this process.

@@ Line 54: / Line 54: @@
 [[File:Wiki Keramik CIP Fig 04 english.jpg|thumb|center]]
-Figure 4: Preparation of the system for the CIP cycle a.) Closed system b.) Attaching the screw to the cover plate c.) Starting the opening process d.) Open system e.) View on the oil-water emulsion f.) Metal cage for placing the encapsulated sample in the CIP device.
+'''Figure 4:''' Preparation of the system for the CIP cycle a.) Closed system b.) Attaching the screw to the cover plate c.) Starting the opening process d.) Open system e.) View on the oil-water emulsion f.) Metal cage for placing the encapsulated sample in the CIP device.
 iv.) '''Closing the recipient:''' After installing the metal cage including the sample in the recipient, the cover plate is closed via the hydraulic lifting system and the screw for fixing the cover plate is removed. The yoke, which absorbs the pressure in the axial direction, is then positioned over the cover plate. A specially designed locking system guarantees the exact position of the yoke in relation to the recipient. The locking bar is manually locked in the pressing position with a lever. Figure 5 shows the individual steps for closing the recipient.
-[[File:Wiki Keramik KIP Abb 05.jpg|thumb]]
+[[File:Wiki Keramik KIP Abb 05.jpg|thumb|center]]
-Figure 5: a., b.) Closing the recipient using the hydraulic lifting device c.) Locking the yoke before starting the pressing cycle.
+'''Figure 5:''' a., b.) Closing the recipient using the hydraulic lifting device c.) Locking the yoke before starting the pressing cycle.
 v.) '''Pressure build-up and dwell time, protection against overpressure:''' As mentioned at the beginning, the pressure build-up takes place by a high-pressure pump which is connected to the interior of the recipient via the liquid transport system. Figure 6 shows the system components relevant for pressure build-up. The desired pressure and the dwell time at this pressure are programmed via the system control display. The pressure is applied at the speed as defined in the program. The run of the pressure curve and the actual pressure can be read directly on the display and on an analog manometer. The cold isostatic press operated on the IEK-1 is designed for a maximum pressure of 4400 bar (440 MPa). To be on the safe side, the pressure in standard operation of the system should not exceed 4000 bar (400 MPa). The system is equipped with a rupture disc as overpressure protection. The rupture disc protects the system from uncontrolled failure and is designed with a safety factor of 1.1 based on the maximum pressure.
 == Applications of cold isostatic pressing ==