Crane Production Process of DQCRANES - Dongqi Crane

Our crane products are mainly consisted of metal structure( which is assembled with main beams, side beams, platform, ladder, railings, and trolley frame, etc), machining parts, purchased parts ( such as, bearings, fasteners, standard parts, etc.),cooperation parts ( such as, the hook) and electrical spare parts, etc. The production process of DQCRANES is showed as the following diagram:

Crane production process diagram

Metal Structure Production Process of DQCRANES

1. Incoming material inspection: The incoming materials such as steel and welding materials will be checked according to related national standards in terms of quality, chemical composition, mechanical strength, etc.
2. Pretreatment of steel surface: The pretreatment of steel structure includes shot blasting and ball blasting to remove the rust, which will make the surface of important parts reach degree Sa2.5 of GB8923 standard.
3. Primer Painting: Primer will be painted right after shot and ball blasting to avoid rusting.
4. Marking off: Mark the shape and processing lines on plate with sample plate, handrail or diagram.
5. Plate-cutting: Plates will be cut by CNC cutting, semi-automatic cutting, shearing and sawing.
6. Plate welding: Plates will be welded together according to requirements by semi-automatic cutter and automatic submerged-arc welding.
7. Flaw detection: The butt weld seams will be detected by ray and ultrasonic.
8. Leveling: Level the plate after connecting.
9. Secondary mark, cutting: Mark the plate off by drawing cutting lines according to the required shape and size and cut them with the semi-automatic cutting machine after connecting, detecting, and leveling. 
10. Assemble: Assemble the plates and profiles together into the metal structure of crane by welding.
11. Flaw detection: The butt weld seams of main parts will be detected again.
12. Assembly (assemblage): Assemble each part according to requirements and special attention is needed to distance between the center of two tracks and the length tolerance of crane bridge diagonal line when the main girder of crane and end carriage are connected into crane bridge.

Metal structure of crane

Machining Parts Production Process of DQCRANES

1. Rough parts: They mainly include cast steel (ZG270-500，ZG340-640 etc.), iron casting (HT, QT), welding parts, (steel plate and welding parts), round steel parts (cut by saw machine).
2. Machining: The mechanical components will be processed by milling, planning, grinding, boring, drilling, insertion, etc., to change the shape, size, surface roughness and eventually make them into qualified ones.
3. Electric Assembly: Assembled by electrician.
4. Bought out items: Items such as motor, reducer, bearing, standard fastener, electrics and other standard parts will be brought according to the configuration table prepared by designing department and the schedule made by process department, which will be assembled according the drawing.
5. Cooperation parts: The cooperation parts refer to those such as the cast steel, iron casting, forging and overall spare parts designed by DQCRANES and produced by other crane spare parts manufacturers, which will checked when they be transported into DQCRANS’ workshop.
6. General assembly of Crane: Assemble each part according to general drawing, such as assemble of hoisting mechanism on trolley, pulley and support stand, traveling mechanism, etc. Some parts have to be removed for the sake of transportation, and assemble them at site, but they have to be trial erected at manufacturer’s site, set welding positioning block on appropriate location for positioning of the second assembly.
7. General Inspection of Crane: After general assembly, quality inspection will be conducted thoroughly according to relative standard and technical requirements, and issue ex-work certification will be issued to the qualified one.
8. Painting:Paints will be selected according to the working environment of cranes.
9. Paint Inspection: It is the final procedure of crane production process, which includes the checks on film thickness, sag and crinkle, etc.
10. Crane Delivery: Transport the product to user.
11. Site erection
12. Acceptance

Crane erection