Development and manufacture of sintered glass filter elements and glass filter units made of borosilicate and quartz glass
STEREON Glassfilters GmbH
57644 Hattert (Westerwald)New on Amplifa
About STEREON Glassfilters
STEREON Glassfilters GmbH (formerly ROBU Glasfiltergeräte GmbH), based in Hattert (Westerwald), is a specialist in the development and manufacture of sintered glass filter elements and glass filter units under the ROBU® and VitraPOR® brands. The portfolio comprises filter plates, filter cartridges, filter crucibles, filter funnels, gas washing bottles, sintered glass pellets, membrane filters, dressing stones for diamond tools as well as customer-specific custom designs. Products are made from borosilicate glass 3.3 (DIN ISO 3585) and amorphous quartz glass with porosities from 1.0 µm to 500 µm according to ISO 4793, ASTM E 128 and BS 1752; sintered membrane filters are temperature-resistant to over 1,000 °C. Production combines modern technology with traditional glassblowing: PLC-controlled sintering furnaces, 5-axis CNC and HSC machining, CO2 lasers with 6-axis robots for automated processing and laser marking. Customers include industries such as pharmacy, chemistry, laboratory/analytics, sensor technology, chromatography, nuclear medicine, medical engineering, biotechnology and environmental analysis. Since 2023 the company has belonged to the QSIL Group; products are delivered worldwide.
- Site
- Hattert
- Processes
- Sintering (High-Temperature Sintering Process), Annealing, Glassblowing (Glassblowing, Glass Apparatus Engineering), Pressing (Glass Forming), Shaping processes for sintered glass (porous and solid molded parts), Precision Machining (5-Axis CNC and HSC Machining), Laser Marking / Laser Processing (Micro-Ablation Processes, CO2 Laser), Development & Custom Design of Glass Filter Solutions
- Materials
- Borosilicate glass 3.3, Quartz glass (amorphous), PTFE, HDPE, Borosilicate Glass 3.3 (DIN ISO 3585), Quartz Glass (Amorphous), High-Temperature Sintering Process, Glass Apparatus Engineering / Glassblowing
- Certificates
- ISO 9001:2015, ISO 9001:2015 (LRQA, valid until 31.07.2029)
- Founded
- 1976
- Industries
- Pharmacy, Chemistry, Laboratory/Analytics, Sensor Technology, Chromatography, Nuclear Medicine
- 01
Analysis & Consulting / Application Consulting
- 02
Development & Custom Designs
- 03
Glassblowing / Pressing (Shaping)
- 04
High-Temperature Sintering in PLC-Controlled Furnaces
- 05
5-Axis CNC and HSC Machining
- 06
Laser Processing and Laser Marking (CO2 Laser, 6-Axis Robots)
- 07
Quality Inspection with Documented Porosity Class
- 08
Shipping / Worldwide Logistics
Materials and Processes
Borosilicate Glass 3.3 (DIN ISO 3585)
Standardized specialty glass with low thermal expansion, dimensionally stable up to approx. 500 °C and chemically resistant to acids, alkalis and organic substances.
Quartz Glass (Amorphous)
For filter plates, sintered membrane filters and high-temperature applications with temperature resistance up to over 1,000 °C.
PTFE
Used for hose connections and accessory components of the glass filter systems.
HDPE
Plastic used for sintered balls/pellets in the accessories range.
High-Temperature Sintering Process
Manufacture of porous and solid sintered glass molded parts with defined pore sizes down to below 1.0 µm at 35 % open porosity in PLC-controlled furnaces.
Glass Apparatus Engineering / Glassblowing
Craftsmanship-based manufacture of laboratory glass apparatus, glass filter units and custom designs to customer specifications.
5-Axis CNC and HSC Machining
Precision machining of glass for complex geometries with consistently high dimensional accuracy.
Laser Processing and Laser Marking
Automated glass processing and individual marking with CO2 lasers on 6-axis robots, without pollutant-containing paints.
Annealing
Stress-relief annealing to avoid permanent stresses in borosilicate glass 3.3.
Hattert Site
Hattert
DEHeadquarters, Production and Shipping
- Lot size
- One-off production through to series production
- Materials
- Borosilicate glass 3.3, quartz glass, PTFE, HDPE
- PLC-controlled sintering furnaces
- 5-axis CNC/HSC machining center
- CO2 lasers with 6-axis robots
- Glassblowing / glass apparatus engineering
Sintered Glass Components
Inside the production
Industries
Processes & technical limits
| Processes | Tolerance | Max. part | Weight | Lot size | Materials |
|---|---|---|---|---|---|
| Sintering (High-Temperature Sintering Process)Heat Treatment | – | – | – | – | Borosilicate glass 3.3, Quartz glass |
| AnnealingHeat Treatment | – | – | – | – | Borosilicate glass 3.3 |
| Glassblowing (Glassblowing, Glass Apparatus Engineering)Casting | – | – | – | – | Borosilicate glass 3.3, Quartz glass |
| Pressing (Glass Forming)Forming | – | – | – | – | Borosilicate glass 3.3 |
| Shaping processes for sintered glass (porous and solid molded parts)Casting | – | – | – | – | Borosilicate glass 3.3, Quartz glass |
| Precision Machining (5-Axis CNC and HSC Machining)Machining | – | – | – | – | Borosilicate glass 3.3, Quartz glass |
| Laser Marking / Laser Processing (Micro-Ablation Processes, CO2 Laser)Surface | – | – | – | – | Borosilicate glass 3.3 |
| Development & Custom Design of Glass Filter SolutionsEngineering | – | – | – | – | Borosilicate glass 3.3, Quartz glass |
| Quality Inspection (Documented Porosity Classes, Quality Control)Testing | – | – | – | – | – |
| Manufacture of Sintered Glass Membrane FiltersCasting | – | – | – | – | Borosilicate glass 3.3, Quartz glass |
| Manufacture of Sintered Glass Dressing Stones for Diamond ToolsCasting | – | – | – | – | Borosilicate glass 3.3 |
3 Anlagen & Maschinen
| Machine | Manufacturer / model | Quantity | Working area | Year built | Site |
|---|---|---|---|---|---|
| 5-axis CNC machining center (HSC) | – | – | – | – | Hattert |
| PLC-controlled sintering furnaces | – | – | – | – | Hattert |
| CO2 lasers with 6-axis robots (automated manufacturing/laser marking) | – | – | – | – | Hattert |
Additional services
Quality and Standards
Quality management is certified to DIN EN ISO 9001:2015 (LRQA). Every filter element is inspected and quality-controlled with a documented porosity class according to ISO 4793 (as well as ASTM E 128 and BS 1752).
| Evidence | Hattert |
|---|---|
| ISO 9001:2015 (LRQA, valid until 31.07.2029) |
History from ROBU to STEREON
- 1976
Foundation of the company ROBU in Hattert by Oskar Thiel on 1 January.
- 1985
Construction of the new office and production building at today's site.
- 1987
Conversion into ROBU Glasfiltergeräte GmbH on 19 November.
- 1988
Stephan Curland takes over the management on 1 January (until 31.01.2025).
- 1995
Expansion of production: new production hall and separate shipping area.
- 2002
New construction phase with additional warehouse and shipping space.
- 2017
Establishment of an own department for glass apparatus engineering.
- 2019
Expansion of the plant with new warehouse space.
- 2023
ROBU becomes part of the QSIL Group (QSIL SE, Thuringia).
- 2024
Expansion of the product range to include glass filters made of quartz glass.
- 2025
Benjamin Schmidt becomes Managing Director; renaming to STEREON Glassfilters GmbH as of 22.12.2025.