**Process Specification for the**

**Trimming and Drilling of Composites**

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| **Engineering Directorate**                                           |
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| **Structural Engineering Division**                                   |
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| ### May 2007                                                          |
|                                                                       |
| ![](media/image1.png)                                                 |
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| National Aeronautics and                                              |
|                                                                       |
| Space Administration                                                  |
|                                                                       |
| **Lyndon B. Johnson Space Center**                                    |
|                                                                       |
| Houston, Texas                                                        |
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**Process Specification for the**

**Trimming and Drilling of Composites**

+--------------------+--------------------------------+-----+----------+
| **Prepared by:**   | ####                           |     |          |
+--------------------+--------------------------------+-----+----------+
|                    | Michael E. Fowler, Jr.,        |     | Date     |
|                    | Materials and Processes        |     |          |
|                    | Branch/ES4                     |     |          |
+--------------------+--------------------------------+-----+----------+

+--------------------+--------------------------------+----+----------+
| **Approved by:**   | ####                           |    |          |
+--------------------+--------------------------------+----+----------+
|                    | Brad Files, Branch Chief,      |    | Date     |
|                    | Materials and Processes        |    |          |
|                    | Branch/ES4                     |    |          |
+--------------------+--------------------------------+----+----------+

  ----------- --------------------------------------------- ---------------
  REVISIONS                                                 

  VERSION     CHANGES                                       DATE

  \--         Original version                              6/18/97

  A           Author change                                 7/22/99

  B           Reviewed per QMS requirement. Removed         10/16/02
              references to old division name. Removed      
              reference to DPI-6000 series (not             
              applicable).                                  

  C           Reviewed per QMS requirement. No changes.     3/8/05

  D           Updated reference to JPR 8500.4. Updated      
              section reference in paragraph 3.2.           
  ----------- --------------------------------------------- ---------------

**1.0 SCOPE**

This document provides the standard requirements for the trimming and
drilling of composite parts.

# **2.0 APPLICABILITY**

This specification shall be applicable whenever a composite trimming or
drilling process is invoked per Section 3.0, "Usage".

**3.0 USAGE**

This section gives the requirements for the proper use of this process
specification.

In accordance with the drawing and part definition requirements of JPR
8500.4, "Engineering Drawing System Manual", a standard composite
trimming or drilling process may be invoked by providing a process note
in the applicable drawing or CAD model as illustrated in Figure 1.

Figure 1. Example of a process note for a composite trimming process.

**3.1 LEVELS**

The \"Level\" designator governs the extent to which quality assurance
provisions are applied and shall be specified in the process note on the
basis of the following definitions:

a\. [Level 1]{.underline} --- Level 1 processes shall include the
practice of the quality assurance provisions as required by Section 7.1.
Whenever invoking these Level 1 provisions, the designer should also
consider calling out an NDE process specification on the drawing or CAD
model.

b\. [Level 2]{.underline} --- Level 2 processes shall include the
practice of the quality assurance provisions as required by Section 7.2.

**3.2 EDGE SEALING**

If desired, specify the sealing of trimmed or drilled part edges in the
process note and be sure to specify the sealing material. Sealants shall
be applied per Section 6.6.

**3.3 NON-DESTRUCTIVE EVALUATION**

This specification does not address the application of non-destructive
evaluation (NDE) methods. However, when calling for Level 1 processing,
the designer should also consider the use of NDE inspection by calling
out a separate NDE process specification on the drawing or CAD model.

**4.0 APPLICABLE DOCUMENTS**

The following references were used in developing this process
specification:

SOP-007.1 A, *Preparation and Revision of Process Specifications*

JPR 8500.4, *Engineering Drawing System Manual*

The following documents are called out as an extension of the
requirements given in this specification:

ANSI/NCSL Z540-1, *Calibration Laboratories and Measuring and Test
Equipment General Requirements*

**5.0 MATERIAL REQUIREMENTS**

**5.1 PART MATERIALS**

Part materials to be trimmed or drilled shall satisfy the requirements
of any applicable material specifications given on the applicable
drawing or CAD model.

**5.2 SEALANTS**

Any applicable sealants shall remain chemically inert with respect to
the part material (or materials) throughout the extent of processing.
Sealants shall be stored in an environment as specified by an applicable
Material Data Sheet (MDS). Contractors shall obtain applicable MDS's
from JSC Manufacturing before processing. If a suitable MDS does not
exist, then the sealant vendor's storage requirements shall apply.

**6.0 PROCESS REQUIREMENTS**

**6.1 WRITTEN PROCEDURES AND STANDARDS**

For work performed at JSC facilities, written procedures shall be used
and they shall consist of Detailed Process Instructions (DPIs) selected
for use from DPI-6003- series of work instructions. MDS's shall also be
used internally.

For contracted work, refer to the contract for requirements concerning
the use of written procedures. If an edge sealant is specified, then the
Contractor shall also obtain applicable Material Data Sheets (MDS) from
JSC Manufacturing before processing.

**6.2 FACILITIES**

Composite trimming and drilling facilities shall be performed in a
Safety-approved airflow booth or area. This facility shall provide
adequate airflow with which to remove airborne dust particles. Be sure
that all trimming and drilling operations are performed outside of
controlled clean room areas.

**6.3 FIXTURES AND JIGS**

Work pieces shall be held securely using suitable mechanical fixtures or
jigs during trimming and drilling operations. Any mating surfaces on the
fixtures or jigs shall be clean and free of debris in order to prevent
damage to the part.

**6.4 TRIMMING AND DRILLING OPERATIONS**

Trimming and drilling shall be performed using carbide or
diamond-impregnated cutting tools. Trimming and drilling material feed
rates and cutting speeds shall be selected so as to provide safe machine
operation and to prevent unacceptable defects or dimensional
inaccuracies as defined in Section 7.0.

**6.5 PERSONAL SAFETY**

Safety precautions shall be followed as defined by an applicable
Material Safety Data Sheet (MSDS).

**6.6 SEALING OF EDGES**

Sealants will be applied to trimmed edges as defined by the drawing or
CAD model. Sealants shall be applied and cured in a safe manner
according to an applicable MDS. If a suitable MDS does not exist, then
the sealant vendor's application instructions shall be used.

**6.7 HANDLING AND STORAGE**

Composite parts shall be handled safely and stored in a manner that
prevents damage and visible contamination from occurring to the part.

**7.0 PROCESS VERIFICATION**

**7.1 LEVEL 1 PROCESS VERIFICATION**

A second-party visual inspection, or Mandatory Inspection Point (MIP),
of the trimmed part or drilled hole edges shall be performed for Level 1
processes prior to the application of sealant. All visible edge defects
(e.g., chips, cracks, delaminations) shall be formally reported as
discrepancies using standard procedures. Note that additional process
verification shall be employed if an NDE method is specified (see
Section 3.3).

**7.2 LEVEL 2 PROCESS VERIFICATION**

A first-party visual inspection of the trimmed part or drilled hole
edges shall be performed for Level 2 processes in which all visible edge
defects (e.g., chips, cracks, delaminations) shall be formally reported
as discrepancies using standard procedures.

No second-party inspection is required for Level 2 processing.

**7.3 VERIFICATION RECORDS**

Traceable records for all second-party inspection shall be kept as
quality assurance records.

**8.0 TRAINING AND CERTIFICATION OF PERSONNEL**

No formal training is required for drilling or trimming technicians.
On-the-job training is satisfactory for hand held drilling or trimming
pending that safe shop work practices are being followed and records are
kept of OJT personnel.

**9.0 DEFINITIONS**

First-party inspection Inspection performed by the manufacturing
technicians performing the work.

Second-party inspection Inspection performed by an individual other than
the technician performing the work specially authorized to perform
second-party inspection.