Started a SMT PCB assembly unit

Why did i buy the T-960 reflow oven?

The reason i send my boards for assembling is,

The parts are extremely difficult to hand solder as i use 0402 and QFN package parts in most of my designs. The 0402 parts are terrible for hand soldering as they are almost invisible and cant even be held in a tweezer properly.

The assembling cost for smaller number of boards is very high, Like suppose we have to get only 5 boards made costs me around Rs.800/- per board. That’s very bad when we want to manufacture a low cost product without large volumes or on demand in 1 or 2 nos.

Thats’ what happened with my VALTRACK-V2 GPS tracker. It costed me Rs.800/- per board to get them soldered with 5 days lead time. So i had to increase the cost of the device to compensate for the assembling charges, which will have a bad effect on sales.

Long story short, i wanted to bring down the costs and get boards done quickly in house and provide faster turn around time for my clients in the whole design process.

So i did some research on ovens and found one of my client had a set up of Puhui T960 reflow oven. It was a not so big machine with conveyer type chain system to move boards across its 5 heating zones. It has a LCD display and button interface for setting the temperature waves for different soldering profiles. It had been on my wishlist since a long time. The time had arrived and i got the machine for around Rs.1.5 lakhs from a Delhi based distributor. The machine was shipped by VRL logistics and man, when i went to pick up the machine to VRL warehouse, the view was terrible and i was in a shock to see how they really ship the parcels. They treat them like garbage, throwing around the parcels and standing on top of one box to get another. I was terrified thinking what the condition of my expensive machine would be.

Then i found my parcel unloaded and kept in a corner. My first expression looking at the machine package was, Whaaat ! I ordered this?
I was under the impression that it would be a table top machine as it had been long time i had seen the device. I didn’t know it was so big. The machine is quite big and it needs around two big tables to sit comfortably. Next we saw that the machine came packed in an aluminum frame covered with plywood sheets. I was somewhat relieved that packaging was done well and machine should be alright.

We paid around Rs.2500/- to VRL and then around Rs.300/- to a trolley vehicle to drop the machine at my house.
Reason to ship the machine to my house is that my office has old wiring system and has an old Energy meter with maximum capacity of around 10A. The machine manufacturer had told that the machine to be used with a 3 phase power source or from a 3.5 kW capable Single phase power source. My house wiring is newer with the energy meter of 0-30A energy meter, so i chose to shift the machine to house and test it out for some days and then plan to shift the machine to other place.

Shipping the machine was a headache as the machine didn’t pass through the door as it was bigger than the door by few inches.

So we tilted the machine vertically and took the machine inside and placed on my single bed and started installing the device.

Connection and wiring :

Installing the machine is quite simple,

Just connect the power and its good to go. For single phase wiring you have to short the L1,L2,L3 lines and give to Phase line of Single phase source and Neutral of source to ZeroWire and Earthing to Earth wire.

We have used 4 square mm wires to power the machine directly from the energy meter instead of tapping into the house wiring as the machine is power hungry and it might burn the wiring if its not thick enough to deliver the large currents needed.
We did a mistake and bought a three core 4 square mm wire from Nikson which is some cheap bad quality wire, It gets heated and becomes warm and loses its stiffness when machine is running. If run for long time it might melt away, But i am using it for now. Soon will change to a better wiring, may be a separate three wire wiring instead of single 3 core cable.

But we didn’t take care of the fuse and blew the fuse on first attempt as it was using a very small thread in it suitable for house hold loads. When we increased fuse wire thickness we were good. We also installed a separate 32A MCB for protection.

The energy meter readings say 1.5kW to 1.6kW when machine is running. The current is around 22A when all heating zones are ON. Current drops after the needed heating temperature is achieved.

T-960 has 5 heating zones and they can be set to different temperatures pre-selected in 8 different waves settings. You can choose any temperature profile among the 8. You can change the temperatures of each zone up or down using the buttons.
When all the zones reach the desired temperature then we can start the conveyer belt and put the boards from left and they will get reflowed and come from the right side opening of the oven.

The initial experience has been good and we have experimented with soldering and have had good results. We did some mistakes like applied excess lead and it lead to shorts but now we have learnt from it.

The first board ever to be reflowed in the machine are the VALTRACK-V2 boards as shown here,

Will keep experimenting and keep you guys posted on the learning curve.

And If you have SMT boards to be reflowed, send them over. We will be providing Assembling services too.

Also see :

Started a SMT PCB assembly unit – #MakeInIndia

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