The window and door industry is a very old industry. With the emergence of many new materials in recent years (such as aluminum alloy, broken bridge aluminum, aluminum exterior and interior wood, UPVC, etc.), the production and assembly of doors and windows has also shown diversity. Here is a general summary of the assembly methods of windows and doors, the equipment used, the calculation of cutting dimensions, etc.

1. The main assembly methods of windows and doors:

There are four ways to assemble windows and doors: welding, corner connector crimping connection, plug-in screw connection, and rivet and tenon connection. Among them, rivet and tenon connections are mainly used for wooden windows and will not be introduced here.

 1.1 Welding: Mainly used for the assembly of UPVC window and door frames, sash, and mullion. Because a certain length of the profile needs to be melted during the welding process, a certain length of "welding allowance" must be reserved at the long end of the profile when calculating the cutting size.

There are two main methods: "corner welding" and "middle welding".

Corner welding: generally refers to the two ends of the frame and sash material being cut into 45-degree angles and then welded with a welding machine;

（picture 1）

Middle mullion welding: generally refers to cutting the two ends of the middle mullion profile into a "^ shape", opening a "V-shaped" opening on the frame and sash profile, and then welding it with a special welding plate;

（picture 2）

l Cost-effectiveness analysis: Equipment investment and welding costs are high, strength is low, and sealing performance is very good

l Equipment used: double head cutting saw, V cutting saw, welding machine

l Connection medium: None (connected by autogenous melting)

l Blanking calculation:

1)The two ends of the frame, sash and middle mullions + welding allowance respectively

2)Depth of V-port of frame and sash - one welding allowance

(double head cutting saw)

(V-cutting saw)

(Four head welding machine)

1.2.Corner connector joints: mainly used for broken bridge aluminum alloy windows and doors, some ordinary aluminum alloy  window and door frames, and sash corner connections. Generally speaking, after the two ends of the frame and sash profile are cut into 45-degree angles, they are assembled into a whole using special connectors, corner crimping machines and screws. Although this method also cuts 45-degree angles at both ends, it does not require welding, so there is no need to reserve welding allowance at both ends.

l Cost-effectiveness analysis: The equipment investment and assembly costs are high, the strength is very good, and the sealing performance is good.

l Equipment used: professional double head cutting saw, corner crimping machine

l Connection medium: corner connectors (corner connector, etc.), self-tapping screws

l  Calculation of blanking: No need to add or subtract welding allowance at both ends of the frame and sash profile

1.3. Plug-in screw connection: Generally speaking, it refers to using a special milling cutter to mill the two ends of the horizontal (frame,sash ) according to the end shape of the vertical (mullion) material, and then using screws to assemble the horizontal and vertical (frame, mullion) into a whole.

In this assembly process, it is divided into two steps:

1）Both ends of the vertical (frame, sash) profile are cut flat

2）After processing and shaping the two ends of the horizontal (frame, sash) material, insert the vertical material and tighten it with screws. Or: Mill the connecting parts of the vertical (frame, sash) materials flat, and then insert the flat-cut horizontal materials into the vertical materials and tighten them with screws.

l Cost-effectiveness analysis: Equipment investment and assembly costs are low, strength is not high, and sealing performance is poor.

l Equipment used: End milling machine

l Connection media: mullion connectors (or: mullion flanges), screws, fixing sheets, waterproof sheets, etc.

l  Calculation of blanking:

1、Longitudinal (frame, sash) materials are calculated based on actual length;

At both ends of the horizontal (frame, sash) material, the "connection thickness" of the vertical material must be subtracted.