Structure of Bonding Machine

The main difference between the so-called bonding mixer and the common mixer is that the mixing process of the bonding mixer has a special treatment step of warming up and softening and bonding. This feature makes it more suitable for the mixing of metal-based powder coatings, i.e. metal powders. The metal powder coating mixed by the Bonding Mixer has many advantages such as high gloss, good leveling, good metal fidelity, saving metal pigments, and recyclable landing powder. Although the ordinary post-mixer can also mix metal powder, but its performance is far from the effect of the Bonding mixer. Because of this, Bonding mixer is being more and more metal powder manufacturers are aware of and pay attention to. This paper will introduce to discuss its production application related issues.

l Structure of Bonding Machine

l Bonding process steps

Structure of Bonding Machine

Bonding (Bonding) process was originally introduced by Benda-Lutz when mixing metal effect powder, later, many powder coating plants have applied this technology. Bonding Mixer has a single-cylinder and two-cylinder models. Single-cylinder type is the first generation of products, bonding and cooling are in the same cylinder, the appearance and flip mixer is similar, but the shape of the mixing paddle and the speed of the mixing paddle is different. Nowadays, it is mostly a double-cylinder type, where the bonding cylinder and cooling cylinder are not the same cylinder. In this way, the bonded powder coating can be cooled quickly, with small probability of caking and less loss, and the powder utilization rate is close to 100%.

Bonding mixing unit is composed of main and vice mixing paddle, material cylinder, frame and electric control, temperature control system, nitrogen gas ventilation system. Where the powder can be contacted (main and secondary stirring paddles, material cylinder) there is a sandwich layer that can be cooled down quickly by circulating cooling water to prevent the agglomeration of powder and the bonding on the paddle and pot wall.

It is worth mentioning the PLC intelligent control system of the bonding machine, which can be programmed according to the user's needs. Insufficient nitrogen or circulating water failure will be automatically alarmed, and the next operation cannot be carried out until the failure is removed; each stage of the process can be programmed and controlled, and the machine will automatically run according to the programmed speed, time and temperature, and can also be programmed to control the upper protection current and upper protection temperature of each step, or the time, current and temperature co-protection (co-protection means that the running time, upper protection current or upper limit temperature, one of the three reaches the set value, the device will stop the operation of the stage, directly into the next stage of operation, effectively prevent clumping).

Bonding process steps

Each manufacturer's equipment has its own process control characteristics, but they all have three stages of process control: the heating stage, the bonding stage and the cooling stage. The operation of each stage may also vary, but the basic theory is the same. However, the flexibility of programming the three stages is a sign of advanced equipment. The following is a reference process for the Bonding operation.

1. 4,1 Programming according to the product process requirements: setting the friction heating speed (or electric heating rate), the boning temperature, the boning speed and time, the cooling cycle, and the synergistic protection values for time, upper limit temperature and upper limit current (almost to the glass transition temperature, when the powder changes from powder to agglomerate and the current increases significantly).

2. Using nitrogen as the inert protective gas, after determining the nitrogen concentration, the machine is started and the powder coating primer to be bonded is added to the bonding cylinder.

3. The primer is heated by friction (or electrically) to a certain temperature. Add the metallic effect pigment according to the prompt, and after reaching the bonding temperature, the machine will automatically run according to the parameters of the bonding stage.

4. The bonding stage should be maintained steadily for a certain period of time, at which time the operator takes a sample online and verifies the bonding temperature by manual operation.

5. If the bonding temperature drifts, fine-tune the program parameters online until the temperature of the bonding stage matches with the actual one, and then instruct the machine to run automatically according to the program.

6. After the bonding stage is completed, the bonding powder automatically enters the cooling cylinder for quick cooling according to the program to prevent caking and ensure the product quality.

7. After the program passes the verification of one or two kettles, the batch of priming powder can run automatically directly according to the set program.

Conclusion

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