ALTA also qualitatively excels in the area of processing internal and external tube surfaces for stem and telescopic stem preparation suitable for external chrome plating, both in welded and weldless material.
ALTA performs tube straightening and turning preemptively by removing all defects that are always potentially present in both hot and cold tubes, making them ready for adjustment and chrome plating operations.
As well as giving the tube straightness and roundness ( external sanding in tolerance grade 8 and max roughness 0.4 Ra), non-aggressive machining avoids the formation of micro fractures in the metal structure: lesions that could otherwise give rise to cracks, fissures or damage the chrome plated surface after chrome plating.
ALTA trusts in selected and validated partners for chroming with an in-line chrome plating technique, providing homogeneous and continuous chrome plating quality down the entire length of the stem.
All stems can undergo a passivation process to increase the chrome plating’s resistance to weathering. Chrome plated stems undergo salt spray resistance tests of up to 120 H with a rating of 9.
All parts produced are validated by ALTA and accompanied by the relevant production certificate.
General data sheet for chrome bars
| Standard | EN 10267 | EN 10083-3 |
| Dimensional Range | OD min 10 mm - OD max 250 mm |
| Lenght | max 9300 mm
(fixed lengths or custom cuts on request) |
| Configuration | +N Normalized – Hardened – Induction hardened |
| Internal tolerances | Grade 7/8 |
| Unique characteristics | anti-microcracking treatment |
| Steel quality | CK45 – 20MNV6 – C53 – 42 Cr Mo 4 |
| Chrome thickness | 15 my +/- 3 my from OD 20 mm - 25 my +/- 5 my over 20 mm |
| Chrome firmness | 850 - 1150 HV |
| Surface Characteristics | 0.2 my Ra; 2 my Rt (UNI ISO 468/91) test according to ISO 1456/1458 according to ISO 4540 Rating 8-10 |
| Test Certificate | EN 10204:2004/3.1 |
| Automatic control | NSS up to 200 H rating 9 |
