Optical devices
Adjustment and positioning of components, adjustable mounts, focusing mechanisms. The ST7192 brass ball cage is the one specifically recommended by Steinel.
Official distributor in Spain
Guide elements
mini series
The line of guide pillars, guide bushes and ball cages for miniature and precision die sets. Materials hardened to 62 ±½ HRC and diameters from 3 mm.
Diameters
Ø 3 – 10 mm
Hardness
62 ±½ HRC
Part numbers
4 · ST7190/91/97/92
Guide bush standard
DIN 9831 / ISO 9448
01
What are mini series guide elements?
The downsized version of the standard guide element range for die sets: they keep the technical properties of the regular series — case-hardening, ground and lapped finish, preloaded fit — brought down to dimensions below the standard DIN 9825 range.
They are used not only in die sets but also as structural components in high-precision electrical and optical instruments, measuring and metrology equipment, precision machinery and mechatronics.
The guide pillar + ball cage + guide bush set forms a preloaded precision guiding system.
02
The four standard part numbers
Each guide bush part number is compatible with the pillars and ball cages of the same series by nominal diameter. Expand one to see its datasheet, photo, dimensioned drawing and dimension table.
01 Mini series guide pillarST7190 · Guide pillar
Diseño y materiales
| Material (Ø ≥ 8) | 1.7131 (16MnCr5) case-hardened |
|---|---|
| Material (Ø 3–6) | 1.2379 |
| Hardness | 62 ±2 HRC |
| Guide diameter | ISO h3 |
| Mounting bore | ISO P6 (press fit) |
| Finish | Ground and lapped |
The 1.7131 (16MnCr5) is a case-hardening steel with a tough core. For the smallest diameters (3–6 mm), 1.2379 is used, with greater dimensional stability after hardening — relevant where thermal distortion is comparatively more critical.
Tabla dimensional
| d₁ h3 (mm) | l (mm) | Item number |
|---|---|---|
| 3 | 30 · 40 · 60 · 80 | ST7190 03 × … |
| 4 | 50 · 60 · 80 · 100 | ST7190 04 × … |
| 5 | 50 · 60 · 80 · 100 | ST7190 05 × … |
| 6 | 60 · 80 · 100 · 125 | ST7190 06 × … |
| 8 | 80 · 100 · 125 · 160 | ST7190 08 × … |
| 10 | 80 · 100 · 125 · 160 | ST7190 10 × … |
02 Mini series plain guide bushST7191 · Plain guide bush
Diseño y materiales
| Material | 1.3505 (100Cr6) hardened |
|---|---|
| Hardness | 62 ±1 HRC |
| Outer tolerance | h5 |
| Mounting bore | ISO H6 |
| Accessory | SZ9742 (Loctite adhesive) |
| Mounting | Secure with adhesive; do not press in |
The 1.3505 (100Cr6) is the classic bearing steel: high hardness, excellent wear resistance, dimensional stability. Critical: mini plain guide bushes are NOT press-fitted — radial pressure deforms the ID and alters the clearance. They are bonded with adhesive on clean, grease-free surfaces.
Tabla dimensional
| d₁ h3 | d₂ | d₃ h5 | l (mm) |
|---|---|---|---|
| 3 | 5 | 7 | 10 · 20 · 30 |
| 4 | 6 | 8 | 10 · 20 · 30 |
| 5 | 7 | 10 | 10 · 20 · 30 |
| 6 | 9 | 12 | 20 · 30 · 40 |
| 8 | 11 | 15 | 20 · 30 · 40 |
| 10 | 13 | 19 | 20 · 30 · 40 |
03 Mini series guide bush with adhesive groovesST7197 · Grooved guide bush
Diseño y materiales
| Reference standard | DIN 9831 / ISO 9448 |
|---|---|
| Material | 1.3505 (100Cr6) hardened |
| Hardness | 62 ±1 HRC |
| Outer tolerance | js4 |
| Mounting | Secure with adhesive; do not press in |
| Range | Ø 6–10 mm |
It features adhesive grooves machined on the outer surface that hold the adhesive, ensuring uniform fixing that resists accidental pull-out. It is the recommended variant when formal standard certification is required — it is referenced to DIN 9831 / ISO 9448. For smaller diameters (3–5 mm), the option is the plain ST7191.
Tabla dimensional
| d₁ h3 | d₂ | d₃ js4 | l₁ (mm) −0.2/−0.5 |
|---|---|---|---|
| 6 | 9 | 12 | 15 · 20 · 25 · 30 · 40 |
| 8 | 11 | 15 | 20 · 25 · 30 · 35 · 40 |
| 10 | 13 | 19 | 20 · 25 · 30 · 40 · 45 |
04 Mini series ball cageST7192 · Ball cage
Diseño y materiales
| Cage material | Brass 2.0401 |
|---|---|
| Balls | Hardened steel · quality class 1, sorted |
| Length tolerance | ±0.1 mm |
| Compatibility | ST7190 + ST7191/97 of the same Ø |
It is made exclusively in brass 2.0401 because it combines high wear resistance and dimensional stability, both critical in small parts. The balls are quality class 1 (the most demanding class in ISO 3290 / DIN 5401) and sorted — dimensionally screened to guarantee the nominal preload with no radial play.
Tabla dimensional
| d₁ (mm) | d₂ (mm) | l ±0.1 (mm) | Item number |
|---|---|---|---|
| 3 | 5 | 10 · 20 · 30 | ST7192 03 × … |
| 4 | 6 | 10 · 20 · 30 | ST7192 04 × … |
| 5 | 7 | 10 · 20 · 30 | ST7192 05 × … |
| 6 | 9 | 20 · 30 · 40 | ST7192 06 × … |
| 8 | 11 | 20 · 30 · 40 | ST7192 08 × … |
| 10 | 13 | 20 · 30 · 40 | ST7192 10 × … |
03
How to assemble a mini series set
Assembly follows the pattern of a standard die set, with two critical dimensional particularities: the guide pillar is press-fitted (ISO P6) and the guide bush is bonded with adhesive, never press-fitted.
-
1ST7190Guide pillar
ISO P6 · press fitIt is mounted in the lower die shoe bore with an ISO P6 fit (press fit, no additional retainer). Apply oil — never grease — during assembly.
-
2ST7192Ball cage
Free insertionIt is inserted over the pillar, free of stress. The quality class 1 sorted balls maintain the nominal preload with no radial play.
-
3ST7191/97Guide bush
Adhesive · do not pressIt is NOT press-fitted. It is bonded with Loctite adhesive (SZ9742) on clean, grease-free surfaces, in the upper die shoe.
PRELOAD
As the die closes, the guide bush seats over the ball cage with preload controlled by the h3 (pillar) + h5 or js4 (guide bush) tolerances.
Shall we talk about your project?
Tell us about your use case and our engineering team will advise you on choosing the optimal solution in miniature die sets.
04
Applications of mini series guide elements
They cover the dimensional range where standard DIN series fall short, or where a compact, purpose-built geometry is preferable.
Measuring equipment
Dial indicators, internal micrometers, probing mechanisms where the guiding must be free of play.
Electronic connectors
Progressive dies for very low-profile terminals with sub-millimeter tolerances.
Micro-stamping
Fine blanking of thin sheet: watchmaking, medical devices, microelectronics.
Mechatronics
Miniature linear positioners, low-stroke actuation mechanisms.
Modular construction
Standardized small-size die sets with instrumentation-grade guiding.
05
Frequently asked questions
01 Why does the ST7190 guide pillar change material depending on the diameter?
For diameters 8 to 10 mm the material is 1.7131 (16MnCr5) case-hardened — a case-hardening steel with a tough core that handles cyclic bending well. For diameters 3 to 6 mm it is 1.2379, a tool steel with greater dimensional stability after hardening: in very small-diameter pillars the thermal distortion from the treatment is comparatively more critical, and a steel with less distortion is preferable. Both variants reach 62 ±2 HRC and work with ISO h3 tolerance.
02 What is the difference between the ST7191 and the ST7197 guide bush?
ST7191 is the plain version, in 1.3505 (100Cr6) hardened, outer tolerance h5, mounted in ISO H6 and bonded with adhesive; it covers Ø 3–10 mm. ST7197 is the version with adhesive grooves on the outer surface, same material and hardness, outer tolerance js4 and referenced to DIN 9831 / ISO 9448 (formal standard compliance); it covers Ø 6–10 mm. The ST7197 is preferable when certification is required or when the adhesive grooves are needed for a robust bond. Both: bonded with adhesive, not press-fitted.
03 Why can't mini guide bushes be press-fitted?
Radial pressure on a small-diameter guide bush deforms the internal diameter. In standard die sets (Ø ≥ 16 mm) a deformation of 5 µm is negligible compared with the nominal clearances; in miniature die sets (Ø 3–10 mm) those same 5 µm can represent a significant percentage of the clearance and push the preload out of tolerance. That is why Steinel specifies bonding with Loctite adhesive (SZ9742) on clean surfaces: the fixing is robust without introducing any deformation.
04 Why is the ST7192 mini ball cage made only in brass?
Because brass (Brass 2.0401) combines the two critical properties for small parts: high wear resistance (the material mass is small, so durability per unit volume matters) and dimensional stability against thermal variations and aging. The aluminum or plastic versions of the larger cages are not offered in mini series because their advantages (mass reduction, chemical resistance) do not offset the lower durability in instrumentation applications, where the cage must last the entire life of the device.
05 How long can a pillar be in the mini series range?
The range goes up to 160 mm in length for pillars 8 and 10 mm in diameter; at the other end, 3 mm pillars from 30 mm in length. The choice must consider the length-to-diameter ratio: very high lengths relative to the diameter drastically reduce stiffness under lateral load. As a reference (Steinel curves for standard pillars): increasing the diameter by a factor of 1.68 reduces deflection by 87.5 %. For significant radial loads it may be preferable to reduce the length or move to a larger diameter — the Surisa technical team can help size the set.
Ready to specify your mini series guide elements?
We distribute the complete Steinel Normalien range in Spain. We advise you on part numbers, combinations by nominal diameter and delivery times.