Solution for Retrofitting Old Cut‑to‑Length Lines to Improve Shearing Quality

Many factories have cut‑to‑length lines that have been in service for over a decade. Though the machines can still operate, their shearing quality can no longer meet increasing requirements. The finished sheets suffer from inconsistent lengths, large burrs on cutting edges, and unstable flatness. These inherent defects become prominent when higher product standards are required. Manufacturers either keep running the equipment with heavy sorting and scrap loss, or consider purchasing brand‑new machines. In fact, the shearing quality of many old cut‑to‑length lines can be significantly improved by upgrading key components. Several aspects should be considered for retrofitting old cut‑to‑length lines.

Poor shearing performance of old cut‑to‑length lines usually stems from the following critical components.

First, low accuracy of length‑measured feeding. Feeding on many old lines relies on mechanical positioning or conventional motors, resulting in inaccurate feeding lengths and dimensional deviations of sheets. Upgrading to servo‑driven length‑measured feeding with encoders for real‑time length feedback enables automatic stopping at preset positions. This delivers precise shearing length and greatly improves dimensional consistency of sheets.

Second, manual adjustment of shear blade clearance. On legacy lines, operators adjust blade clearance manually with feeler gauges. Re‑adjustment is needed for every change in material thickness, and adjustment quality heavily depends on workers’ skill. Improper settings cause burrs. Automatic shear‑blade‑clearance adjustment can be retrofitted. Operators input material thickness and grade, and the system calculates clearance automatically. It stabilizes burr control and shortens material‑grade changeover time.

Third, insufficient leveling capacity. Leveling units on old lines often have worn rollers or insufficient back pressure, leading to poor leveling effect, curved strips, inaccurate cutting dimensions and uneven sheets. The leveling roller system can be upgraded: replace worn rollers and optimize the back‑pressure structure to enhance leveling performance. Straight strip material is essential for guaranteed shearing quality.

Fourth, outdated control systems. Some old lines still adopt obsolete relay‑logic controls, which complicate parameter setup and fault diagnosis. Upgrading to a PLC‑based control system with a touch‑screen offers intuitive parameter entry, convenient recipe management and clear fault alarms for easier operation and maintenance.

Supporting units should also be inspected during retrofitting. For stacking, automatic stacking devices can be added to replace manual stacking for neat sheet stacking. For material feeding, automatic coil‑loading trolleys can be installed to realize automatic coil centering and feeding. These auxiliary upgrades raise the overall automation level of the whole line.

A major advantage of retrofitting old cut‑to‑length lines is that complete line replacement is unnecessary. Major existing components such as uncoilers and main bodies of shearing machines can be retained. Only key feeding, shearing and control sections require renewal. No modifications to workshops or foundations are needed. The retrofit cycle is short with minimal disruption to production.

Nevertheless, retrofitting is subject to the original mechanical condition of the line. If mechanical parts are heavily worn with deformed frames or loose blade holders, simple electrical and control upgrades will not suffice. On‑site assessment is required to compare the feasibility between retrofitting and full replacement. Before renovation, an experienced supplier should conduct an on‑site inspection to identify root causes of poor shearing quality and work out targeted retrofit solutions.

Guangdong Ruihui Intelligent Technology Co., Ltd. has over 20 years of experience in stamping automation and is a national Specialized, Refined, Differential and Innovative “Little Giant” enterprise. Headquartered in Dongguan, the company employs more than 400 staff including over 80 R&D engineers. Ruihui has completed numerous retrofit projects for old cut‑to‑length lines. Starting with on‑site evaluation, the company identifies root causes of shearing‑quality defects and implements targeted upgrades for servo length‑measured feeding, automatic shear‑blade‑clearance adjustment, leveling roller systems and PLC control systems. Auxiliary upgrades including automatic loading and automatic stacking are also available. Retrofit projects feature short lead‑time and limited production interruption. Nearly 5,000 sets of Ruihui‑manufactured equipment are running for domestic and overseas clients. The company serves well‑known OEMs and Tier‑one suppliers such as BYD, Geely, Volkswagen, Tesla, BMW, Mercedes‑Benz, Honda and Jaguar Land Rover, accumulating rich practical experience in legacy‑line retrofitting.