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Impact Value vs Placement Force

Views: 2474

#79951

Impact Value vs Placement Force | 10 March, 2018

Dear expert`s i am need some information regarding what is different between Impact Value and Placement Force.

Normally we only used Placement Force for Pick and Place Machine.

Any expert`s can explain for Impact Value? Thank You

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#79955

Impact Value vs Placement Force | 12 March, 2018

I also like to know the difference as well. Thanks!

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dwl

#79966

Impact Value vs Placement Force | 13 March, 2018

Placement force usually refers to the amount of force an SMT nozzle applies to a part when placing it. You want enough force to push the component onto the paste but not so much that you damage the part. Some specialized applications involve placing through hole components with the SMT machines and this may require extra force from the nozzle.

I've never heard the term "Impact Value". Is this specific to one type of machine? It may just be what one machine maker calls Placement Force.

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#79971

Impact Value vs Placement Force | 14 March, 2018

Thanks for the explanation? I will try for it. lol

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#79978

Impact Value vs Placement Force | 15 March, 2018

Impact is the instantaneous force at the time the component first reaches the PCB. F=M*a....so the acceleration is the key factor. If charted on a graph it would look like a spike...higher force for a short duration. The placement force is typically less force for longer duration and happens after the impact force (almost like a heart beat on a heart monitor).

On older model placement systems the impact force was more of a factor as the Z axis drive systems were not as sophisticated as on the machines being produced today (accept for the entry level machines perhaps). In some cases the Z axis was even driven pneumatically and the motion profile difficult to control.

Motor driven axis are also varied in their control methods, some better than others. In the quest for higher placement rates manufacturers needed to move the Z axis very quickly as the Z motion is the biggest factor in cycle rate. But controlling the impact force is problematic without a sophisticated system which controls the motion precisely so that the Z axis can be driven all the way to the PCB at high speed and slam on the brakes just before the impact (to minimize this force and reduce component cracking).

In order to accomplish this, typically sensors are required to measure the exact height of the component (bottom) and the exact height of the PCB (mounting surface) at the precise mounting location for each component.

It is safe to say that lower costs machines may indeed be able to have low impact force but naturally this means slow placement rates. Knowing the actual force is sometimes wishful thinking and based upon theoretical. For example, some systems will know that a spring loaded nozzle will yield different forces based upon the amount the spring is deflected. So the nozzle is driven to a certain height based upon the desired placement force figuring in component thickness (measured or assumed), nozzle length (measured or assumed) and board height (measured or assumed). Measured systems (in real time) are always better.

Higher speed machines with more sophisticated drive systems will cost more naturally. Some will even have closed loop feedback meaning the placement force can actually be measured during the actual component placement.

I could go on but hopefully your initial question has been answered...

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#80265

Impact Value vs Placement Force | 18 April, 2018

Hi Sir,

Thank you for information and explanation. From your explanation i`am imagining the different Impact Value and Placement Force work like this.

Please refer my attachment file..

Nirmal.Viallzoon

Attachments:

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#80278

Impact Value vs Placement Force | 19 April, 2018

Exactly...I can't say that is what you might see with today's more sophisticated machines but that is a good representation of what I have seen personally.

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