Not every manufacturer needs to own a deep hole drilling machine. For low-to-medium volume production, prototype runs, or holes that require specialized capabilities, contracting a DHD service provider is often the most economical choice.
But selecting the right provider is not straightforward. The wrong choice can mean scrapped parts, missed deadlines, and damaged customer relationships. This guide provides a structured evaluation framework covering what to check, what to ask, and how to make the final decision.
1. When to Outsource vs. Buy
| Factor | Outsource to Service Provider | Buy Your Own Machine |
|---|---|---|
| Annual volume | < 1,000 holes/year | > 5,000 holes/year |
| Hole variety | Multiple sizes, materials | Dedicated production |
| Lead time | Flexible | Need quick turnaround |
| Capital available | Limited | Budget available |
| Existing capacity | No DHD machine or operator | Have facility and team |
| Core competency | DHD is not core to your business | DHD is a key process |
For a detailed cost comparison, see the Total Cost of Ownership Guide and New vs Used Machine Guide.
2. Technical Capability Checklist
Equipment
Before sending an RFQ, verify the provider’s equipment matches your requirements:
| Question | Why It Matters |
|---|---|
| What is their maximum drilling depth? | Your part may exceed their stroke |
| What diameter range can they handle? | Gun drilling (1–50 mm) vs BTA (20–250+ mm) |
| What materials have they worked with? | Inconel and titanium require different parameters than steel |
| What is their maximum L/D ratio? | Some providers cap at 50:1; others do 200:1+ |
| Do they have counter-rotation capability? | Critical for straightness in long holes |
| What is their coolant pressure capacity? | 40 bar is minimum; 100 bar needed for superalloys |
See Gun Drilling vs BTA Machine Guide for method capability details.
Quality Certifications
| Certification | Required For | What It Covers |
|---|---|---|
| ISO 9001:2015 | All manufacturing | Quality management system |
| AS9100 / AS9120 | Aerospace | Aerospace-specific quality + traceability |
| Nadcap | Aerospace heat treat/surface finishing | Process-specific accreditation |
| ISO 13485 | Medical devices | Medical device QMS |
| IATF 16949 | Automotive | Automotive quality standard |
Sources: 4umachining precision drilling guide; NetSuite contract manufacturing selection guide.
Inspection Capability
| Check | Why It Matters |
|---|---|
| Do they have CMM? | For dimensional verification |
| Do they have surface finish measurement? | Ra/Rz verification |
| Can they measure straightness? | Critical for deep hole quality |
| Do they provide first-article inspection reports? | Required for PPAP |
| What is their scrap rate? | Indicator of process control |
3. The RFQ Process
What to Include in Your RFQ
A complete RFQ should include:
| Item | Details |
|---|---|
| Drawing | Full dimensioned print with tolerances |
| Material | Grade, condition (annealed/hardened), hardness |
| Hole specifications | Diameter, depth, L/D ratio, blind or through |
| Tolerance | IT grade, straightness, roundness |
| Surface finish | Ra or Rz requirement |
| Quantity | Annual volume, batch size, expected frequency |
| Timeline | Required delivery date, prototype vs production |
| Quality requirements | Inspection reports, certifications needed |
Red Flags in RFQ Responses
| Red Flag | Why |
|---|---|
| Quote without reviewing your drawing | Missing critical requirements |
| “We can handle anything” without specifics | Likely lacks specialized DHD knowledge |
| Price far below competitors | Cutting corners on tooling or inspection |
| Unwilling to provide references | Hiding quality issues |
| No first-article inspection offered | Cannot validate process capability |
4. Pricing Structure and Cost Drivers
While specific per-hole pricing varies widely by location, complexity, and volume, the cost is driven by these factors (Rapid-protos cost guide):
Primary Cost Drivers
| Factor | Cost Impact |
|---|---|
| Depth-to-diameter ratio | L/D = 50 costs 2–4× more than L/D = 10 |
| Material | Stainless steel: +20–50% over carbon steel; hardened alloys: +50–100% |
| Tolerance | IT7 costs more than IT10 |
| Surface finish | Ra < 0.8 μm adds finishing cost |
| Batch size | Small batches carry higher per-part setup cost |
Typical Pricing Approach
Most DHD service providers price per hole based on:
- Machine time (the dominant factor at 70–85% of total cost)
- Tooling cost per edge (amortized over expected tool life)
- Setup cost per batch
- Material handling
5. Provider Evaluation Framework
Use a weighted scoring matrix to compare providers objectively.
Recommended Weighting
| Category | Weight | What to Evaluate |
|---|---|---|
| Technical capability | 20% | Equipment, materials experience, max L/D |
| Quality systems | 20% | Certifications, inspection equipment, scrap rate |
| Cost competitiveness | 15% | Per-hole pricing, tooling costs, setup fees |
| Delivery reliability | 15% | On-time delivery record, lead times |
| Communication | 10% | Response time, technical knowledge |
| References | 10% | Customer feedback, repeat business |
| Location | 10% | Shipping cost, face-to-face access |
Scoring Template
| Provider | Technical (20) | Quality (20) | Cost (15) | Delivery (15) | Comm. (10) | References (10) | Location (10) | Total |
|---|---|---|---|---|---|---|---|---|
| Provider A | ||||||||
| Provider B | ||||||||
| Provider C |
6. Due Diligence Checklist
Before awarding a contract:
| Check | Action |
|---|---|
| □ | Factory tour or virtual video walkthrough |
| □ | Sample part order (small batch before volume production) |
| □ | Reference calls with 2–3 current customers |
| □ | Review of NDA and IP protection terms |
| □ | Financial stability check (audited statements or credit report) |
| □ | Quality manual and recent audit results review |
| □ | Confirmation of calibration schedule for inspection equipment |
Sources: NetSuite; Tapecon contract manufacturing guide; Baker Industries.
7. Provider Profile — What to Look For
Ideal Provider Characteristics
| Attribute | Why It Matters |
|---|---|
| Specializes in DHD (not general CNC shop) | Deep hole drilling has unique requirements that general shops may not understand |
| Offers both gun drilling and BTA | Can recommend the right method, not just what they have |
| In-house inspection | Faster feedback, fewer external dependencies |
| Experience with your industry | Understands your quality and documentation requirements |
| Clear communication | Responsive, technically knowledgeable contact |
| Reasonable minimum order | Can handle prototype runs as well as production |
8. Contract Terms to Include
| Term | What to Specify |
|---|---|
| Scope of work | Exact hole specifications, quantities, timelines |
| Pricing | Per-hole price, setup fees, tooling costs, shipping |
| Quality agreement | Acceptance criteria, inspection reports required |
| Warranty | Responsibility for non-conforming parts |
| IP protection | Ownership of tooling, confidentiality |
| Termination | Notice period, transition assistance |
| KPIs | On-time delivery %, defect rate, response time |
9. Summary
| If you… | Recommended Action |
|---|---|
| Have < 1,000 holes/year | Outsource — lower total cost |
| Need multiple hole sizes/materials | Outsource — one provider handles variety |
| Require AS9100 or Nadcap | Outsource — specialist likely already certified |
| Have > 5,000 holes/year, stable design | Consider purchase — lower per-hole cost at volume |
| Need fast turnaround | Outsource to local provider |
| Need prototype then production | Outsource — lower risk for changing designs |
Key Sources
- Rapid-protos, “Deep Hole Drilling: Methods, Tolerance & Cost Guide” — cost driver analysis
- 4umachining, “Precision Drilling Services: What You Need to Know” — quality certification requirements
- NetSuite, “How to Select a Contract Manufacturing Partner” — supplier evaluation framework
- Tapecon, “10 Areas to Consider When Selecting a Contract Manufacturer” — evaluation criteria
- Baker Industries, “Outsource Smarter” — strategic sourcing methodology
- Parts-Badger, deep hole drilling services — pricing model reference
- IPROS GMS, integrated machining services network — outsourcing network model