REG NASA-LLIS-0575-1997 Lessons Learned Numerically Controlled (NC) Milling Removal of Machine Debris.pdf

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1、Lessons Learned Entry: 0575Lesson Info:a71 Lesson Number: 0575a71 Lesson Date: 1997-04-14a71 Submitting Organization: JSCa71 Submitted by: Brian Lamonde & Dave WheelerSubject: Numerically Controlled (NC) Milling: Removal of Machine Debris Description of Driving Event: 1. During the machining and rem

2、oval of tooling tabs located in a small closed pocket on a bulkhead, one of the loose tabs became entrapped in an adjacent corner. The end mill subsequently struck this loose tab, causing ti eject, resulting in damage to the product. The damage was found to include a bent rib and an approximately 2-

3、inch crack The operator was trained but inexperienced in this particular machining operation.Cutter path verifications using software simulations are useful for detecting most types of part / tooling collision programming errors, but they cannot anticipate how detached tabs (or other waste material

4、or debris) may fall into the a pocket, tooling, etc., and be struck by the mill. On any automated (or manual) machining process, detached parts or debris must be accounted for so they do not hamper the process.2. Cost of rework estimated at $10K.Lesson Submitted from the Boeing International Space S

5、tation (ISS) Lessons Learned Database:a. from Boeing ISS dated 4/14/97, was entitled “NC Programming: Tooling Tab Removal“b. from Boeing ISS dated 4/15/97, was entitled “Bulkhead Damaged During Final N/C Milling“Lesson(s) Learned: Removal of debris or waste must be verified during any automated or m

6、anual machining process.Recommendation(s): a71 Consider programming the milling sequence to allow for tabs (or other waste material) to be detached and verified as removed before making additional passes with mill.Provided by IHSNot for ResaleNo reproduction or networking permitted without license f

7、rom IHS-,-,-a71 Verify that machining waste/debris will not accumulate or become entrapped in the product, tooling, or equipment and result in a hazardous condition during the machining operation.a71 Ensure that training, procedures and instructions properly highlight this operational hazard.Evidenc

8、e of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): N/AAdditional Key Phrase(s): N/AAdditional Info: Approval Info: a71 Approval Date: 1997-10-31a71 Approval Name: Ronald A. Montaguea71 Approval Organization: NA3a71 Approval Phone Number: 281-483-8576Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-