Karl Mayer HKS Retrofit: The Complete Modernization Guide
Everything you need to know before retrofitting an HKS 2, HKS 3 or HKS 4 warp knitting machine: scope, timeline, ROI and technical decisions.
Karl Mayer HKS warp knitting machines are workhorses — many units built in the 1990s and 2000s are still producing high-quality tricot fabrics today. The mechanical platform is excellent. What ages is the electronics: obsolete boards, unsupported HMIs, drives that no longer have spare parts. This is where an electronic retrofit becomes the smartest investment: a fraction of the cost of a new machine, and another 15 to 20 years of production.
Why retrofit an HKS rather than replace it
A new HKS 4 costs between €400,000 and €600,000 depending on gauge and options. A full SITM NEXT retrofit sits between €80,000 and €140,000, and reuses the mechanical frame, needle bars and comb bars you already trust. The ROI is typically 18 to 30 months based on avoided downtime and productivity gains from a modern HMI.
What a complete HKS retrofit covers
- Electronic let-off system — closed-loop tension control, replacing mechanical governors.
- Electronic take-down — precise fabric traction, programmable per pattern.
- Electronic guide bar control — for HKS-EL variants and jacquard bars.
- Weft insertion module — when the machine produces weft-inserted technical fabrics.
- Touchscreen HMI — modern interface, recipe management, pattern library, alarms.
- Schneider Electric drives and PLCs — 20-year spare-parts availability guaranteed.
- Remote support & SCADA integration — every SITM NEXT is Industry 4.0-ready out of the box.
Typical HKS retrofit timeline
From order to production ramp-up, expect 10 to 14 weeks: 4 weeks of engineering and hardware preparation in France, 2 to 4 weeks of on-site installation and commissioning by SITM technicians, and 2 to 4 weeks of operator training and fine-tuning. The machine is typically producing sellable fabric within 3 to 5 days after power-on.
HKS 2, HKS 3, HKS 4: what changes
All three platforms are retrofit-friendly. HKS 2 (2 guide bars) is the simplest — usually a 6-8 week engineering scope. HKS 3 and HKS 4 (3 and 4 bars) add complexity on guide bar control and pattern management, especially on EL variants with electronic guide bar drives. Terry towel variants (KS 4 FBZ) follow the same logic with dedicated pattern control.
Frequently asked questions
Can I keep my existing needles and sinkers?
Yes. The retrofit only touches electronics, drives, HMI and — optionally — let-off and take-down modules. Mechanical wear parts are unaffected.
Is the retrofit compatible with older HKS from the 1990s?
Yes. SITM NEXT is a universal platform designed for every Karl Mayer HKS generation from the 1980s onward, plus KS, COP and Liba Copcentra.
Do I need to send my machine to France?
No. SITM technicians install and commission the retrofit on-site, anywhere in the world. We work in EN, FR, ES and PT.
What warranty do you offer?
12 months on all electronic modules, extendable to 24 or 36 months with a service contract.
Ready to modernize your HKS?
Send us your machine model, serial number and year of manufacture — you get a detailed retrofit proposal within 5 working days.