×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Calculating Time of a Peck Drilling Cycle on Milling Machine

Calculating Time of a Peck Drilling Cycle on Milling Machine

Calculating Time of a Peck Drilling Cycle on Milling Machine

(OP)
I am looking for a formula to calculate the time of a peck drilling cycle. I have several deep holes to drill in a job I am quoting. I am looking for a formula that I can enter in these variables: hole depth, peck size, drilling feed rate, Rapid feed rate, clearance amount. This cycle retracts from the hole after every peck, and returns to the "clearance amount" at bottom of hole.

Example of variables:

Hole Depth: 25"
Peck Size: .125"
Drill Feed Rate: 3 Inches Per Minute
Rapid Feed Rate: 150 Inches Per Minute
Clearance Amount: .020"

See attached picture for clarification of cycle.

RE: Calculating Time of a Peck Drilling Cycle on Milling Machine

The only unknown is your machine's acceleration/deceleration ramp for rapid-to-feed transition and direction reversal. Other than that, it's just adding up the numbers.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

RE: Calculating Time of a Peck Drilling Cycle on Milling Machine

(OP)
Machine acceleration/deceleration is minimal and not even a factor to bother with for my purposes. I don't see how I can just add up the numbers. The problem is calculating the distance every time you peck, you retract all the way out of the hole and then back in. That distance will increase every time you peck. I want a formula that I can use with different variables.

RE: Calculating Time of a Peck Drilling Cycle on Milling Machine

If you divide the hole depth by peck/step travel, that will give you the number of pecks. In your case, 25 inches depth / .125 = 200 pecks. You will likely end up with a short peck due to the 0.020 clearance, as the machine will feed that distance instead of rapid, and it will not exceed 0.125 per peck. Rapid time must be included for this peck.

So 201 pecks with a total feed distance of 25.020 inches, multiplied by your feedrate. Then, you will be rapiding between 0.020 and -25.000, so take the average of those 2 values (12.510 inches) and multiply by the number of pecks, divide by the rapid rate, and that will equal your total rapid time.

You can easily put together a spreadsheet in excel to plug in your variables and arrive at an answer.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

RE: Calculating Time of a Peck Drilling Cycle on Milling Machine

Be sure to account for rapid in and rapid out on your average distance. For all practical purposes, you can use the value of your total depth, and just not multiply it by 2 for both the in and out travels, but I personally like to treat it seperately. It stays more well organized in my mind that way.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources