Increasing Production of In-die Tapping Operation with Servo Press

Increasing Production of In-Die Tapping Operation

How much faster can a servo press run an In-die tapping application than with a traditional mechanical press using the following traditional process requirements?

Press:  10" stroke (Box B14)

Tap size:  M8 x 1.25 

Material:  1008-1010

Part thickness:  Extruded hole with tap length of .250"(Box B8)

Production Speed:  38 SPM (Box B169)

Press stroke used for tapping:  5.30" (Box B98)

Gear Ratio:  1.9:1(Box B98)

Having to use a full press cycle on a traditional mechanical press, 4.70" of press stroke is used for feeding the strip into progression.  However, using a servo press’s pendulum (half) motion http://youtu.be/i7wSG5UHJec, we can eliminate any unused stroke length and gain increased production rates without having to change current process specifications.

In this scenario, only 1.5” of stroke length is necessary to advance the strip into progression.

Combine this with the 5.30” required for tapping, our necessary stroke length is 6.80”.  By removing the 3.2” of stroke, we will increase production rates from 38spm to 54 spm.

Figure 1

Here’s how. 
A test was performed on a SEYI SD1-220T direct drive servo press with a maximum stroke length (TDC) of 9.84”.  In Pendulum (Half) mode, we can virtually re-adjust TDC to meet the required process stroke of 6.80” or 173mm:  This re-adjusted stroke is programmed into the pendulum (Half) motion profile as setpoint “P1” (see figure 1). 

When the press is engaged, we descend from TDC (250 mm/9.84”) to P1 (143mm/6.8”) at 50 spm (rated max press spm).  P1 is set to 173mm (6.81”) above BDC.  We then descend from P1 (173mm) to P2 (135 mm) at 50 spm.  The distance between P1 and P2 is the 1.5” that we need for the feed progression.  We want to use 50spm between these two pints in order to save as much time as possible.  At P2 (135mm/5.3”), our tapping begins.  We slow the press speed down to 38spm to match the process requirements. We carry this through to bottom dead center (P3), and then back up to P4 at the same rate.  From P4 back up to P1, we increase the speed back to the rated 50 spm.  Note that “0” is used instead of programming 50. The controller software knows that, upon ramp-up, if a 0 is used, it means maximum press spm.  You could just as easily program 50 spm and get the same result.

Figure 2 shows indicates the forming curve and at what points the feed progression and tapping occur.

Figure 2

To see the video of new adjusted output, go here. http://youtu.be/_ALcszI7SU8

New Tapped Hole Size App

We often get requests for the appropriate hole sizes for taps.  While we have a rollform tap hole size chart in the In die tapping resources section of our website, there is a new downloadable app that takes this information to the next level.   North American Tool Corporation has developed a Thread Tap App that can be downloaded to any Apple, Android, Kindle or desktop device.  In addition to hole size information for both cutting and rollform taps, they also give general recommendations for torque and horse power requirements for tapping along with a myriad of other good technical information about taps and tapping.

The app can be downloaded by visiting North American Tool’s website at www.natool.com.   Click on the Mobile Apps button and choose the app for your appropriate operating system.  If you have any additional technical questions or need to order taps please contact us at 800-332-3230.

Tap Change for Hutchison Tool In-die Tapping Units

Tap Change for Hutchison Tool In-die Tapping Units

We often hear that a picture is worth a thousand words.  Enclosed is an educational/training video as to how to change taps and set tap depth height in the Hutchison In-die Tapping Units.  This would be an excellent video to share with your toolroom people, setup personnel and press operators.  Please contact us at info@hutchisontool.com for more information.

Tapping Head Temperatures

In-die Tapping Head Operating Temperatures

As a general rule, most In-die tapping heads run at high production speeds.  In some cases the production speeds can reach up to 200 strokes per minute.  These higher production speeds leads to heat which often brings up questions about how hot the In-die tapping heads can get while in production. 

Normal bearing operating temperatures can range from 80-150F degrees but are rated up to 220F degrees.   Bearing temperatures normally run hotter at start up and right after re-lubrication because excess grease causes friction and drag in the bearing.  Temperature spikes of 50F degrees at start up and 30F degrees after re-lubrication are common.  With all this information our recommendations are not to exceed 170F degrees during continual operation but understanding that there may be spikes up to 200F degrees at startup or re-lubrication. 

New Horizontal In-die Tapping Head

New Horizontal In-die Tapping Head

The overwhelming majority of In-die tapping applications are best suited to be tapped with the tap coming down vertically and tapping the strip in the flat position.   What happens when a hole cannot be tapped in the flat due to concerns of hole distortion after forming or maintaining a hole location after parts are formed?  In the past these would be applications that could not be tapped in the press and would have to go to a costly secondary tapping operation.

The new HTS Model 6300 Horizontal tapping head now allows for tapping of parts in the press that were formerly not possible.   The new HTS Model 6300 is designed specifically to each individual application due to the unique nature of each horizontal tapping application.  Please contact us with your application and we can provide recommendations and technical specifications.

As always, we look forward to hearing from you regarding your In-die tapping, secondary tapping or other tapping applications.  Please contact us at 800-332-3230 or e-mail us at sales@hutchisontool.com

Quick Change Tap Positioning in Press

The most popular feature of our In-die tapping heads is the ability to quickly change taps in the press in under a minute.  It is important when changing taps in the press to change taps consistently at the same ram position in order to maintain the correct tap timing.  We recommend changing the taps when the press is always at top dead center.  This allows for the maximum opening in the press to access the quick change pitch assembly as well as providing a consistent starting position for tap change.

Visual Thread Inspection of Form Threads

Visual Thread Inspection of Form Threads

When using form thread taps it is important to be aware that form threads visually have a slightly different look than a cut thread.  All formed threads have a cup or “U” in the crest due to the nature of the thread forming process.  A properly sized hole should result in a thread percentage of 65-75%.  Tapping with too small of a pre-tap hole size results in excessive tapping torque, tap wear and possible tap breakage.   Enclosed is a link on our website to a tapped hole size guide for rollform taps. (http://www.hutchisontool.com/pdf/tapped_hole_size_guide.pdf)