Prevent Lead Time Delays on Custom Crossed Roller Bearings

Most late bearing deliveries are not caused by the factory floor. They start in the quote stage, when a drawing is missing a tolerance, a material note arrives after production planning, or a prototype sign-off has no owner. If you are sourcing custom crossed roller bearings for an equipment build with a fixed delivery date, the days you lose are usually lost before the purchase order exists. At BY Bearings, a precision crossed roller bearings manufacturer, we see the same preventable gaps repeatedly, and this article lists them so you can close them first.

Why do custom bearing orders slip before the RFQ is even sent?

Because the RFQ is treated as a question about price, when it is really the start of the engineering review. A supplier cannot quote a bearing it cannot fully define. Each clarification email adds a round trip, and across time zones one question can cost two to three working days.

The delay usually comes from four places: the drawing, the tolerances, the approval process, and the material. Each can be fixed on your side while specifications are still flexible. After the order is placed, the same fixes cost more, because tooling, steel and grinding slots may already be committed.

Boundary: a complete package shortens the quote and engineering phase. It does not remove the physical production time for heat treatment, grinding and inspection. We would rather tell you that now than promise a number that does not hold.

Which missing details create the most preventable production delays?

The table below compares the four most common causes of delay with what they trigger on our side and how you can prevent them. This is the section to forward to your design and purchasing teams together.

Gap in the RFQ package	What it triggers	How to prevent it
Incomplete drawings (no mounting hole pattern, missing chamfers, no seal or cage notes)	Engineering queries, re-quoting, restarted process planning	Send a dimensioned drawing with inner and outer ring details, hole positions and any interface fits
Unclear tolerances (accuracy class not stated, runout and preload undefined)	Wrong grinding route, or conservative assumptions that add cost and time	State the precision class (P5, P4 or P2), required runout, and clearance or preload target
Prototype approval without a decision owner or criteria	Samples wait for sign-off while production slots go to other jobs	Name one approver, define pass/fail measurements, and set a response date before samples ship
Special material or surface requests raised late	Material sourcing, extra heat treatment checks, revised inspection plan	Declare any deviation from standard GCr15 (SAE 52100) or any coating at RFQ stage

Why tolerances cause more trouble than most buyers expect

A drawing that says "high precision" is not a specification. P5, P4 and P2 are different grinding and inspection routes, and our grinding accuracy reaches P2 class with runout controlled within 1.5 μm. If you need that level, say so in numbers. If your application only needs P5, specifying P2 adds cost and can lengthen the schedule for no functional gain.

Why prototype approval deserves its own schedule line

Prototype approval is the delay buyers forget to plan. A sample that reaches your team on Friday and is reviewed three weeks later has effectively added three weeks to the project. Agree in advance what you will measure, such as runout, rotational torque feel, and fit on your housing, and who signs off.

What should a drawing package contain before you request a quote?

Use this sequence. It takes an engineer about an hour and can save a week of correspondence.

1. Confirm the bearing type. Decide whether you need a standard crossed roller design such as the BRE Series Crossed Roller Bearings with changes, or a fully new geometry.
2. Attach a dimensioned drawing. Include bore, outer diameter, width, mounting holes, chamfers and any non-standard features.
3. State the accuracy class and runout. Write P5, P4 or P2 and the measured runout limit in micrometers.
4. Define clearance or preload. Robotic joints and rotary axes often need negative clearance to remove wobble. Say what you need.
5. List load and speed. Give radial, axial and overturning moment loads and the operating speed range.
6. Declare material and surface needs. Standard is GCr15 (SAE 52100) at HRC 60-64. Flag anything else now.
7. Set prototype rules. Quantity, approval criteria, approver name and response time.
8. Give quantity and delivery date. Include trial lot and expected repeat volume. There is no fixed MOQ on our side, so you can quote a trial lot.

When this does not apply: if you are replacing an existing bearing with a direct dimensional equivalent, a sample or a clear photo with measurements plus the original part number may be enough to start. A full drawing is needed once any dimension, hole or tolerance changes.

Buyer's checklist: is your RFQ ready to send?

• Drawing includes every dimension that touches your housing or shaft.
• Precision class and runout limit are written as values, not adjectives.
• Preload or clearance requirement is stated.
• Load case covers radial, axial and moment loads.
• Material and surface treatment are confirmed or marked "standard".
• One named person approves prototypes, with a response time.
• Required delivery date is tied to your assembly start, not to your order date.
• Inspection report needs are listed, such as runout and torque records.

Can a custom order still ship quickly, and what limits that?

Yes, within limits. Our 15,000 sets of monthly capacity and a 13,500 m² intelligent factory with a CNC workshop and automated heat treatment line give us room to schedule custom work alongside standard series. In our experience with OEM supply, a 3 to 6 week turnaround is a realistic target for dimensionally interchangeable or well-defined parts. That target depends on a complete drawing, confirmed materials, and no open prototype loop.

What can extend it: a new geometry that needs fresh process planning, a non-standard material that must be sourced, or a sample approval that waits on your side. We will give a lead time after reviewing your actual drawing, not a blanket promise for all orders.

Quality steps are fixed regardless of urgency. Our system follows ISO 9001, steel is checked by spectrographic analysis, post heat treatment we run metallographic examination, and every bearing gets 100% inspection before shipment. You can read more about this on our Quality Control page. We do not shorten inspection to recover time, because a bearing that fails in your machine costs more than a late one.

What our recent export work shows

We have supplied crossed roller bearings for semiconductor equipment in Germany, and BBH crossed roller bearings in bulk export to Germany. For rotary axes, we have supplied P2 rotary table bearings for gear grinding in Mexico. These cases involve different drawings and tolerances, which is why we start each one with a documentation review instead of a fixed schedule. For compact axes, the BRTM Series Rotary Table Bearings page shows what a catalog baseline looks like before changes.

What are the common mistakes that cost the most days?

• Sending a catalog part number with unlisted changes. If a hole moves or a ring is altered, the part is no longer standard. Mark every change.
• Requesting P2 for every axis. Match the class to the function. A robot joint, a rotary table and a turntable do not need the same grade.
• Leaving preload open. Without it we have to guess, and a guess means a sample revision.
• Adding material changes after the quote. It resets sourcing and inspection planning.
• Starting prototype review without criteria. Approval becomes a discussion instead of a measurement.
• Quoting from the order date. Work backward from your assembly start, including sample time and shipping.

Which application details should you add for faster review?

Application context lets our engineers choose the right internal design without extra emails. For example, a robotic joint needs compact, high rigidity and low backlash, while a CNC rotary table needs tilting stiffness under combined loads. Tell us the end use, whether it is Bearings for Industrial Robotics, a machine tool axis, a direct drive motor, or medical or semiconductor equipment where low vibration and quiet running matter.

Limit: application notes help selection, but they do not replace a tolerance or a drawing. Treat them as a supplement.

Next step

If your build date is fixed, send the drawing, accuracy class, preload requirement, material note and target delivery date together. We will review the package, flag any missing items, and reply with a lead time based on your real specifications. You can get a quote from our engineering team, or ask for selection advice before your drawing is final.