Kitchen Sink Manufacturing Process: Stainless Steel Pressed Sink

As the most popular type of sink on the market, stainless steel kitchen sinks are made through a process of pressing and drawing. Cresheen, a professional sink supplier with over 24 years of industrial experience, uses high-quality stainless steel to create both pressed and drawn sinks.

Kitchen sinks made of stainless steel can be done using two processes: machine pressing or hand-making. The production process for each kind is unique, so in this article, we will focus on the press sink, which is also known as a drawn sink. You'll see that both terms are used interchangeably for this type of sink. In this article, we will use one of Cresheen’s famous pressed kitchen sinks – V22 to illustrate a complete manufacturing process.

Cresheen’s kitchen sinks are made from high-quality stainless steel and are available in both pressed and drawn varieties. Wholesales are also available for those looking to purchase our sinks in bulk. Contact us today to learn more about our kitchen sink manufacturing process.

Process No.1: Raw material cutting

The steel sheets used to make sinks are generally between 0.8 and 1.5 millimeters in thickness. This is the ideal thickness for a sink, as it guarantees the best results possible. The factory will have several steel plates of varying thicknesses that are used for creating different types of sinks; depending on what the final product is intended for, they will select from the available options when putting together a new sink.

The sheet metal is delivered to the factory in coils that are weighed, and the typical width of each sheet is 1220 mm. There is no limit to its length, meaning it can be customized per order. This is then pressed or drawn into shape to make each individual sink.

For V22, before we cut the metal sheet, we will need to inspect the coil width and its thickness, to make sure its width is 800mm and thickness is approx. 0.8mm, which fits our client’s requirement. Then our staff will load the metal sheet coil in the metal sheet cutting machine, which is already programmed to cut V22’s required size. The very first few sheets will be used to adjust the coil line and to test if the cutting size is ideal until the cut dimensions match exactly our blueprint. After careful checking, we will start the automatic cutting programme.

For quality control purposes, 1 per 50 pieces will be sampled and its length, width and thickness will be measured. These measurements with a difference of not more than 5mm between the two diagonals of the sheet, no long scratch marks on the surface of the material visually before cutting, stretch film flat against the material, no folds or flagging, no more than 10mm exposed on both sides of the material, and shear burr height less than 0.2mm.

Process No.2: First-time pressing/drawing

The steel plate is placed on the drawing press machine and drawn through the upper and lower laminated plates reader. The product mold is in opening which can be seen between each workbench. A machine presses until table index finger into allowing it to follow the shape of the mold. The goal at this juncture is to make sure that the first drawing depth mirror image is about 80% off the total design finish line marksthe chirography.

For Cresheen pressed sink, for example, V22, the cut metal sheet will be placed in the lower formwork and the press-forming machine will draw the bowl-shaped according to the die automatically. The upper formwork is placed on the lower formwork and the two will be locked together. Then, the drawing press machine starts to work until it reaches the die stop line. It takes about 20 seconds to 30 seconds to finish this process.

After that, the sink will be taken from the press machine and placed it onto a conveyor belt which then carries it to the next process—trimming.

Process No.3: trimming

The pressed bowl will be placed on the trimming machine, excessive border will be trimmed automatically. For V22, we will need to set the sink’s required size according to our blueprint on CNC machine. The software system is designed especially for the sink industry and can be directly applied on a metal sheet with high precision. With this programme, we can make sure the final sink is with consistent sizes, smooth edges and perfect round corners.

Process No.4: Annealing

Annealing is a heat treatment that restores the stainless steel’s strength which was impacted by the previous drawing process. The sink is placed on an assembly line and heated to a certain temperature until it reaches the annealing point. It is then cooled slowly in order to relieve internal stresses. Specifically, the sink products are run through a furnace that is heated to about 1150 degrees C. The sinks are moved through this part of the process with a crane lock or a conveyor belt.

This step also removes the magnetism from the sink so it will not attract metal objects. This part of production is often outsourced because not all factories can do this process in-house efficiently.

Process No.5: second time pressing and shape truing

The process of drawing the sink is repeated. This time it is done with a mold and hydraulic press. This is to create the design depth. The first drawing was just to create the shape of the sink; however, this second one refines it and makes it useful. To complete its formation, the sink is placed in a mold and then pressed until it reaches the desired shape. The final product should have no longer any scratches on the surface, the material should be flat with no folds or flagging.

For example, V22, our QC team will make sure the annealed bowl is clean inside and free from any other contaminants. Each of the second-drawn bowls will have flat workpiece panels, no wrinkles, no damage, no indentations or cracks and no scratches or scuffs.

Process No.6: bowl-edge refinement

For V22, by using a 300T trimming machine, Cresheen makes sure that the bowl flash is less than 0.2mm, and no crushing, no deformation, no scratches on the surface of the basin, no scratches on the mouth of the basin from the positioning plate. QC team will check the first measurement 690*445*R11.5, each piece is visually inspected for uniform width on all four sides, and every 50 pieces are measured on all four sides with a gauge, and the difference between the widths of the opposite sides is not more than 0.5 mm.

Process No.7: first cleaning

After the sink is trimmed, it will go through the first cleaning process before entering the next stage of production. This is to remove any particles or debris that might have been left behind from the previous steps. The sink is placed on a conveyor belt and goes through a series of cleaning. It is rinsed with water to remove any chemicals that might be left behind. This step is important to ensure that the sink is free from any contaminants before it goes through the next process.

At our automated cleaning line, we heat up the water to 50-70 degree Celsius and degreasers will be added to help remove oil and other stains. QC team is to ensure that no foam in the basin coming out of the rinse line, and no oil stains in the basin, no slippery feeling to the touch.

Process No.8: bowl edge flanging

After the sink is trimmed and cleaned, the next step is to create the flange. The flange is the part of the sink that will be visible after it is installed. It is important to make sure that the flange is level and flush with the sink. This step is done by a machine that bends the metal around the sink to create the flange.

Each client’s requirements are different, some require their sinks to have edge flanging while some don’t. for V22, its edges need to be flanged. This process is done by machine automatically as our engineer will set up the programme each time before the manufacture.

After the sink goes through the flanging machine, our QC team will check the sink to see if there is any deformation on the sink or the flange. They will also measure the sink to make sure that it is the correct size and shape. Quality matters so we also set up an inspection guideline for our V22 kitchen sink. For example:

1. Flanging angle deviation ±2 degrees, uniform height, height difference less than 0.5 mm

2. The four sides should not have a seal mark

Summary

So the above are the first 8 steps for manufacturing a press sink or a drawn sink. There are still more! Follow up on our later articles for more information.