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FAQs --EMS GALLANT HOT AIR REFLOW OVEN----------------------
Q. How many zones are there?A. Unlike conveyorised ovens design it does not have separate zones but it is equivalent to five zones.
Q. In what way it is different from conveyorised ovens ?A. In conveyorised ovens there are panels fixed on top and bottom whose temperature is fixed and the PCB temp. Is set by adjusting the conveyor speed .
There are many variables like controlling temp. of 8/10 panels ( either infrared or hot air), conveyor speed to achieve required temp. which is a quite time consuming process . In Gallant the PCB is kept on a stationary tray and temp. of the heater itself is varied by a microcontroller thus achieving the required temp profile . So physically although only one chamber is there it gives the performance of a equivalent 10 zone oven. Q. How it operates ?A . Please refer to the block diagram on the catalog or in the manual.The PCB’s to be reflowed are kept on tray and a tray motor takes the PCB Inside the oven chamber. The chamber has a Ni-Cr heater which is made on-off by solid state relay which is inturn controlled by a microcontroller. The chamber has a thermocouple kept inside which gives feedback to CPU about temp. inside the oven.The required Temp., time and Ramp can be directly programmed through keyboard and rest is taken care by the CPU.
Q. How a profile can be set ?A. As explained in the Operation manual , it has facility to program following parameters-
a) Preheat temp. T1 deg. C b) Preheat ramp1 c) Soaking time t2 sec. d) Reflow temp. T2 deg.C e) Reflow ramp 2 f) Dwell time at reflow t4 sec. g) Cooling time t5 sec. The required values can be selected by pressing +/- keys. Q.How much time is required to set a profile?A. Approx. 1 to 2 minutes.
Q. What is the cycle time?A. A typical reflow profile takes approx. 6 to 7 minutes.
Q. What is the throughput ?A. Let us a take an example.
PCB size - 4” * 4” NO. Of PCB’s in a tray - 16” * 16” Profile cycle time = 7 min. (420s) Loading & Unloading - 2 min. (120s) Total time for 16 PCB’s- 540 s Average time per PCB - 34s Q. How ramp is achieved?A. As the cycle starts the heater is put ON and the circulating fan dissipates the heat by heating the air by convection currents . The thermocouple inside the oven gives continuous mV input tocontrol card where the analog voltage is converted to digital and the CPU compares it with expected temp. as per the programmed ramp and decides whether to put ON the heater or not.
Q. What is the advantage of Gallant over conveyorised ovens?A. The profile setting in Gallant is very easy, simply by inputting the Temperatures and time and ramp you can get the required profile. Contrary to conveyorised ovens where lot adjustments are required in various panel temp. Conveyor speed etc
Q. What is repeatability?A. If checked by putting a thermocouple on a PCB and running the cycle many times the temp. Variation is less than 2/3 deg.
Q. What is the temp. Gradient across the PCB?A. If four thermocouples are hooked at four points on a PCB the variation is less than 5 deg.
Q. Why profiler is required?A. The Gallant comes in ready to use and calibrated and can function well without a profiler. In conveyorised ovens the profile setting itself requires a profiler mostly built-in . For Gallant profiler can be used to crosscheck the temp. attained.
Q. What is the connected load?A. The connected load is 10 KVA, it draws approx. 40 amp. For 220 V supply.
Q. Is it not power consuming?A. Normally hot air ovens consume more power compared to IR. In this case the heater is put on as per the ramp setting and is made on/off thus average consumption is 50%. Also the heater gets on only when cycle is made ON, unlike conveyor where heater panel remain ON irrespective of PCB is there or not.
Q. How proper convection is achieved?A. The oven design is such to promote proper movement of air. The fan blade is specially designed with profile in such way that hot air is forced in re-circulating way to achieve uniform heating.
Q. Which Microcontroller is used?A. It uses 80c31 microcontroller.
Q. What is the space required?A . The oven is designed with footprint of approx. 1m x 1m .
To get the same profile a conveyorised oven of approx. 2m oven is required. Q. What are safety features?A. Voltage- It has a over-voltage and under-voltage sensing and cutoff.Current- It has short circuit and earth leakage protection with resettable circuit breaker.
Over-temp. - The heater and PCB’s are protected against electrical problem leading to over-temp. By a separate cutoff circuit. Operator safety- Warning labels are put at all points where it is necessary. Beep while tray is coming out. Apart from this the unit conforms to CE requirements as regards EMI /EMC requirements. Q. Whether it can do Glue curing?A. Yes. It can be programmed for Glue curing or epoxy curing.
Q. What is the maximum temp. It can reach?A. It can reach maximum 250 Deg. C.
Q. What is the maximum time for setting ?A. It is 600s. But if Repeat function is used it can be extended further.
Q. Why Batch type ?A. It has following advantages in a typical situations.
1. For small to medium batches setting time is minimum . 2. Flexibility to recall and change profiles quickl;y 3. Saves space 4. Saves power because heater is ON only when cycle is ON. 5. At a time no. Of PCB’s depending on size of PCB. Q. How cleaning is done? A. The oven can be opened from the top side , after removing top cover all parts are accessible.
Q. What is the warm up time?A. Five minutes. As a thumb rule first cycle at the start of the work to be run as dry cycle to allow the temp. to settle at all places in the oven, though oven can get hot to 250deg in first cycle itself.
Q. What is the maximum Size of PCB it can accomodate?A. 16’’x16’’.
Q. What are the Installation requirements?A. 1. Table as per drg. given in the manual
2. Input power cable as per manual 3. External blower to drive away fumes that emanate from the oven. Q. Whether doubleside reflow can be done ?A Yes. Depending upon design of the PCB either one by one or simultaneous reflow is possible.
Q. How many profiles can be stored?A. It can store 50 profiles in the memory.
Q. What is the advantage of 100% Hot Air ?A. It provides uniform heating of the Pcb, without any shadowing effect or popcorn effect common with the Infrared.
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