FAQ
Essential Machining FAQs: Real Answers That Save Your Time and Cost
Looking to avoid costly design mistakes, manage delivery risks, and get faster, more accurate quotes?
This FAQ page is built from real conversations with our global clients—covering everything from drawing best practices to managing Chinese New Year delays. Whether you’re an engineer, buyer, or project manager, these insights will help you make smarter decisions and avoid common pitfalls in CNC and custom parts sourcing.
✅ Learn how to design more machinable parts
✅ Understand how quantity, tolerances, and materials affect cost
✅ Get tips to manage lead time during global holidays
✅ Avoid surprises in surface treatment, threading, and quality control
Need-to-know before you order!
A 3D file is actually not the best document for quoting. This is because a 3D model does not clearly convey key information such as material, tolerances, threads, precision holes, surface treatment, and surface finish—all of which significantly affect cost estimation.
The most preferred file format is a PDF drawing, as it clearly outlines all technical requirements, enabling engineers to quickly understand the part and provide an accurate quote. A 3D file is only needed when the part is extremely complex or has fine details that require further inspection. Otherwise, the 3D model can be provided later during production.
One commonly overlooked detail is the corner radius (R). Many designers model inner corners of cavities as sharp 90-degree angles. However, in CNC machining, tool geometry prevents the cutter from reaching into sharp corners, leaving behind a radius.
The smaller the radius, the smaller the cutting tool required, which increases machining time and cost.
To achieve a true sharp corner, EDM (Electrical Discharge Machining) is needed, which greatly increases cost.
Therefore, keeping the fillet radius and choosing an appropriate R size can significantly help control manufacturing costs.
Yes. The unit price of a part can vary greatly depending on the quantity.
For example, making 1 piece vs 10 pieces: Even though machining time per part may be the same, costs like programming, machine setup, inspection, and logistics are amortized over more units, lowering the per-part cost.
However, increasing from 10 to 20, or 100 to 300 pieces, often doesn’t result in a significant unit price drop.
One key detail often overlooked is China's long national holidays, especially Chinese New Year.
While the official holiday typically lasts 2 weeks, in reality, production is affected for 5–6 weeks:
Workers may leave early to avoid travel congestion and prepare for the holiday.
After the holiday, workers may extend their stay home, especially younger employees who return for matchmaking or weddings.
Even if a factory's in-house staff returns on time, suppliers of materials, plating, or heat treatment may delay, affecting the full production cycle.
👉 Therefore, it’s crucial to plan procurement ahead of time. The earlier you place your orders, the better the chance your shipment will be delivered on schedule.
Key holidays to note:
Chinese New Year 2026: February 12–24, 2026
National Day 2025: October 1–8, 2025
Yes. Our typical lead time is 3–5 weeks, but several factors affect this:
a. Material:
Aluminum and plastics are softer and easier to machine, resulting in shorter lead times.
However, plastic parts may deform easily and require stress relief time during production.
Steel and copper are harder, requiring more machining time. Some materials like titanium are very challenging, prone to tool sticking or fire, and need special cutting fluids, increasing lead time.
b. Heat Treatment:
Steel parts that require quenching/hardening add 1–2 weeks, not just for processing but also due to potential part deformation, which requires careful handling to avoid rejection.
c. Surface Finishing:
Anodizing (clear), blackening, and nickel plating take 1–2 days.
Black chrome on iron-zinc base takes about 3 days.
Silver plating can take 3–5 days or even a week.
Off-season: July–September. Many companies are on summer break, with fewer orders. Placing orders during this period may shorten lead time by 1–2 weeks.
Peak season: October–December. Buyers rush to ship before Christmas, causing tight production capacity and logistics delays. Lead times may be extended by 1–2 weeks.
Chinese New Year impact: Orders placed from February to early March may experience extended lead times due to holiday disruption.
Machining is a broad category. First, determine if your parts are standard or custom (non-standard).
For standard parts, larger factories are more cost-effective.
For custom parts, consider the following factors:
Order quantity:
1–10 units
10–100 units
1000+ units
High-volume parts may require dedicated automation (e.g. auto lathes) to reduce cost.
Part size:
Large parts need large, often specialized equipment not commonly owned by small shops.
Small to medium parts are more universal and easier to source.
Part accuracy:
Higher precision means higher value, and easier long-distance transport due to lighter weight.
But precision requires high-end equipment, mature technology, and strong engineering and quality control capabilities.
Also evaluate the supplier’s:
Reputation
History and market focus
Equipment and inspection capabilities
Engineering know-how
Quotation speed
File documentation quality
Even a small thread can reveal whether a machining supplier has mature and reliable management.
Thread effective depth:
Threads usually taper off at the bottom, meaning the tapping depth needs to be slightly deeper than specified to ensure full engagement.
For thin-walled parts, flat-bottom taps and precise depth control are required to avoid breaking through.Perpendicularity:
Standard inspection uses GO-NO GO gauges. However, after the pass/fail check, it's also important to test the thread’s verticality.
Insert a GO gauge and place a square beside it—if they’re not parallel, the thread is tilted. This can cause assembly issues, especially in large components.Burrs and debris:
Threads should be free from metal chips, burrs, or damaged teeth.
Local rework + deduction:
For minor issues (e.g. missing thread, wrong marking), it's fastest and most cost-effective to fix locally and deduct processing costs from the supplier.Quick replacement:
If parts can’t be repaired, the best solution is for the supplier to quickly remake and ship replacements.Refund/Deduction:
If remanufacturing is not possible due to time constraints, the supplier may issue a refund, allowing the buyer to purchase locally.Return for rework:
If parts are high-value and cannot be repaired locally, they can be shipped back for rework, with all shipping costs covered by the supplier.