Tinplate Printing Inspection and CTP Technology Overview

The specific inspection criteria and methods refer to QB1877-1993 Packaging and Decoration of Tinplate (Chromium-Plated) Printed Products.
Main New Technology: CTP Technology

1. Definition
Computer To Plate (CTP, offline direct plate making)
Computer To Press (on-press direct plate making)
Computer To Paper/Print (direct printing)
Computer To Proof (direct digital color proofing)
Computer-to-Conventional Plate (direct conventional PS plate making)
Currently, unless otherwise specified, CTP generally refers to Computer To Plate, which is an offline direct plate-making system. This system bypasses intermediate processes such as film making or plate exposure. The prepress system’s edited and imposition-ready layout is directly imaged on the printing plate using laser scanning to form the plate.

2. Development History
1960s–1970s: Theoretical research phase
1970s–1980s: Lacked theoretical support, remained in experimental and exploratory stage
1990s: Technology matured and achieved industrial application
1995 DRUPA Exhibition: The official “birth year” of CTP technology
1995–1997: Many large printing companies adopted CTP systems, but costs were high
1997–1998: Prices dropped significantly; small and medium printing plants began adoption
1998–present: Widely applied abroad; in domestic tinplate printing, adoption is still effectively “0”

Figure 3-23 Current Global Application of CTP Equipment

(3) Current Global Application of CTP Equipment
The current global application of CTP equipment is shown in Figure 3-23.
(4) Plate-Making Process
① Laser Imaging Process: The laser imaging process is shown in Figure 3-24.

Figure 3-24 Laser Imaging Process Flow

②Figure 3-25 CTP Direct Plate-Making Process
As can be seen, the CTP process is much simpler compared with traditional laser imaging.
Advantages of CTP Technology:
CTP technology enables the transition from semi-digital and semi-analog prepress processes to fully digital prepress.

Figure 3-25CTP direct plate making process

② It improves work efficiency, simplifies processes, and shortens plate-making time, as well as prepress preparation time.

③ It enhances print quality, as fewer steps make quality control easier.

④ CTP technology ensures reliable use of frequency-modulated (FM) screening.

Limitations of CTP Technology: High cost.

High-Fidelity Printing Technology:

Compared with traditional printing, patterns are clearer, colors are more vivid, and the color gamut is wider. Currently, Hangzhou COFCO Packaging possesses this technology.。