Heat / Utrasonic Staking 2

[mprice]

Hi,

Does anyone know of any technical information about heat / utrasonic staking for joining a plastic injection mouldedpart to a sheet metal part. I want to use one of these processes to avoid using screws but I have found very little technical information. I would like to know what are the pros and cons of the two processes. Specifically: restrictions in terms of head size, clearance for horn diameter, cycle time. Is it possible to make multiple stakes at the same time or are they made individually? etc..
I would be grateful for any feedback.

best regards
Matt

 

[plasgears]

We made plastic gearboxes that had sheet metal heat staked covers. Use alignment features to register the mating parts.

 

[patprimmer]

The resin suppliers literature will give some info. Different resins react differently to ultrasonic and hot iron heat staking.

Both methods can be employed with most plastics.

Companies like Branson should be able to help with more details on ultrasonics.

A simple press with a heated plate with projections to match the moulded pegs should make heat staking a one step process.

It will depend on the polymer, and accurate control of the heat at each stake will be required to get enough melting without sticking.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Cassco]

Hi,

Heat Staking is usually a simpler method of joining parts such as yours. Ultrasonic welding is better suited to plastic-plastic applications where an energy director is designed into the part.

The cycle times are similar and with heat staking you can stake multiple posts at one time.

The key to proper, consistant staking is to have precise control over all machine parameters. (The more demanding the application, the better control required)

The resin suppliers should always be consulted to prevent strength and other properties from being affected by the reheating and cooling of the plastic.

Cheers,

Ken

 

[aspearin1]

I agree with most of the above posts that heat staking is easier and probably cheaper initial investment. With ultrasonics, you may be able to do multiple stakes at once if you rely on the anvil to do the staking, rather than the horn. Basically, the horn will push the entire part and vibrate it onto the stakes of an anvil. Talk to Branson or Stapla(Schunk)about these possibilities and your other application questions. The brighter side of ultrasonics is less power consumption, virtually no heat-up time, durable parts, quick part cooling (a.k.a. faster cycle). I've spent a lot of time in front of both types of machines. From a mere operator comfort point of view, I prefer ultrasonics.

ChemE, M.E. EIT
"The only constant in life is change." -Bruce Lee

 

[Cassco]

It's true that you can stake multiple points with ultrasonics but the machinery is more complex and parts can be expensive. Individual adjustment of the posts will also become more complex and make the balance of the head difficult. If you need faster cycle times you can use cooling tips which will rapidly cool the posts. Just my opinion but I would look to heat staking before ultrasonics.

Cheers,

Ken