Among other things, the sheet form also serves as a seamless base semi-finished product:

• SIPERM® R:
  280 × 220 mm and 250 × 250 mm, thicknesses 2-10 mm
• SIPERM® B:
  Formats up to 1000 × 450 mm, thicknesses 2-10 mm
• SIPERM® HP:
  1000 × 1000 mm and 1200 × 1000 mm, thicknesses 3-20 mm

The sheets have a uniform pore structure and serve as a starting point
for cut-to-size parts, molded parts and welded constructions.

Seamless and welded pipes are available for all three materials.

The pipes are supplied as fully porous semi-finished products, as filter cartridges or as components for structural applications.

Circular blanks and various molded parts are produced using pressing tools. The geometries are based on the existing tool dimensions. After sintering, the pore structure remains formed over the entire cross-section.

The metallic materials SIPERM® R and SIPERM® B can be processed in various ways:

• Rollers
• Bending
• Press
• Embossing
• Milling
• Turning
• Drilling

Important notes:

• Work on surfaces that are relevant to the flow should be avoided.
• Pores can be closed locally by machining processes.
• Water jet cutting and spark erosion are possible without sealing the porous structure.
• When bending, the radius should not be less than ten times the wall thickness.

This machinability makes it possible to transform semi-finished products into geometrically more complex shapes.

SIPERM® HP can be processed in a similar way to engineering plastics:

• Rollers
• Bending
• Milling
• Turning
• Drilling

Additional information:

• Finer pore sizes are more suitable for machining operations.
• Water jet cutting and spark erosion are also possible.
• Moderate temperatures should be used for thermal processing.

SIPERM® R and SIPERM® B

The metallic materials can be joined as follows:

• TIG welding
• Rivets
• Soldering
• Gluing

The surfaces must be clean during welding. A high welding speed is required to keep the heat input low. Filler materials such as GE-316L Si are used for stainless steel and CuSn9 or CuSn10 for bronze.

SIPERM® HP

This material is connected by:

• Hot gas welding
• Heating element welding
• Gluing

Polyethylene welding rods are used as filler materials.

• Counter-current cleaning with gas or liquid
  (cleaning medium must be absolutely clean)
• Brushes with suitable materials
• Hot steam cleaning for SIPERM® R and SIPERM® B
  (for SIPERM® HP only for a short time and up to approx. 100 °C)
• Ultrasonic cleaning for smaller components

Multiple cleaning cycles increase the cleaning effect.

Every material has suitable cleaning media:

SIPERM® R – Stainless steel

• All common solvents (e.g. benzene, carbon tetrachloride, alcohol, acetone)
• Acetic acid up to 25 % (30-60 min)
• Hydrochloric acid up to 10 % (max. 30 min)
• Nitric acid 20 % (30-120 min)
• Alkali and alkaline earth solutions

SIPERM® B – Bronze

• All common solvents (e.g. benzene, carbon tetrachloride, alcohol, acetone)
• Acetic acid up to 25 % (30-60 min) or 20 % (1-2 h)
• Hydrochloric acid up to 10 % (30-60 min)
• Alkali and alkaline earth solutions

SIPERM® HP – Polyethylene

• Acetone
• Ethanol
• Methanol
• Gasoline (room temperature)
• Acetic acid 10 %
• Hydrofluoric acid 40 %
• Hydrochloric acid (any concentration)
• Nitric acid 25 %
• Caustic soda 30 %

SIPERM® materials are produced from defined powder fractions that are first compacted and then sintered. The powder particles bond in such a way that a stable pore space remains between them. The size and uniformity of these pores depends directly on the grain fraction used and the pressing pressure. The entire process is designed in such a way that the pore structure remains reproducible across the entire cross-section of the semi-finished product and the tabulated material parameters are reliably achieved.

The range consists of three material groups: Stainless steel 1.4404 (SIPERM® R), bronze CuSn10 (SIPERM® B) and polyethylene PE-UHMW/HDPE (SIPERM® HP). All three materials are available in several porosity levels so that different combinations of pore size range, porosity, density and strength can be provided. The material series differ in terms of temperature resistance, mechanical properties and media resistance.

Density, porosity, pore size and bubble point value are recorded for each porosity level and permeability values are documented according to standardized procedures. In addition, tensile, shear and flexural strengths can be tested. The tabulated values enable a clear classification of each material quality. As all measurements are carried out on samples of defined geometry, the characteristic values for different material series can be reliably compared.

SIPERM® materials are available as sheets, tubes, circular blanks, candles and molded parts. The dimensions vary depending on the material type: stainless steel has smaller standard sheet formats than bronze, while polyethylene is available in larger sheet sizes. Tubes are available seamless or welded and have a constant pore structure over the entire length. Pressed moulded parts are based on tool geometries and are stabilized in the sintering process, enabling defined contours and thicknesses to be reproducibly achieved.

Metallic SIPERM® materials can be processed using standard metalworking methods, including rolling, bending, pressing, embossing and machining processes such as milling, turning and drilling. It is crucial that functionally relevant surfaces are not compacted. Water jet cutting and spark erosion are processes that are gentle on pores. Polyethylene-based materials can be machined in a similar way to technical thermoplastics; finer pore levels enable more precise machining. Thermal processes are possible, but must remain below the material’s typical limit temperature.

Stainless steel and bronze can be TIG welded, whereby clean surfaces and a high welding speed are required. Suitable filler materials ensure a stable connection. Riveting, soldering and gluing are also possible. SIPERM® HP is joined using hot gas or hot plate welding, whereby the welding wire consists of the same base material. Glued joints are also possible. In all cases, the porous structure must be retained when joining, as it forms the basis of the material function.

Cleaning can be carried out mechanically or chemically. Mechanical methods include counter-current cleaning with gas or liquid, superheated steam, brushing and ultrasound for smaller components. Chemical cleaning agents depend on the material: stainless steel tolerates numerous solvents and acids of limited concentration, bronze can be additionally treated with potassium dichromate, and polyethylene shows high resistance to many organic and inorganic media. After cleaning, complete drying is necessary as residual moisture can influence characteristic values.

The main test methods include bubble point tests to determine the largest pores, permeability measurements to determine the flow properties and porometer measurements to analyze the pore size distribution. Mechanical tests include tensile, shear and bending tests. The results of these methods are documented for each porosity level and are used for material classification. These tests allow the values of the individual material series to be clearly traced and compared with each other.