Preparing the published article.
Comparing Robot Cell Quotes: Arm Cost Versus Cell Cost
A method for splitting robot and cell quotations into arm, cell and service buckets so two bids can be compared on the same basis.
Split Every Quote Into Arm, Cell and Service Buckets
Two quotes for the same payload class rarely cover the same scope, so comparing totals tells you little. Ask each supplier to reissue the quotation in three buckets before you compare anything: the manipulator, everything mounted around it, and everything done on your floor. The arm bucket holds the robot, controller, teach pendant, cable lengths supplied, and any controller-mounted software licences. The cell bucket holds fixtures, grippers, base plate, guarding, safety relays, muting sensors, part-present sensors and interlock hardware. The service bucket holds simulation, offline programming, installation labour, commissioning days, operator training and travel. A supplier who will not split a bundled price is giving you a comparison you cannot make, so record that refusal in the evaluation file.
For each bucket, require a quantity, a unit and a plain statement of what is excluded. A guarding line reading "fencing" is not usable; a line reading "mesh panel, 2 m, three off, excluding floor anchors" is. Say in the enquiry that any line the bidder cannot quantify will be listed as an open item with an owner and a date rather than estimated or guessed. When the three buckets sit on one page, you can see immediately whether a lower total comes from a cheaper arm or from omitted guarding and omitted commissioning days. Keep one column for quantities you supplied yourself, such as base plates fabricated in your own workshop, so those are not counted as savings twice.
Normalise Assumptions Before Comparing Totals
Cost differences usually sit in assumptions rather than hardware, so fix a written basis of comparison and send it to every bidder with the enquiry. State part mass and centre of gravity, required cycle time and how it will be measured, incoming part variation, ambient temperature and dust, available floor space, ceiling height and crane access, power supply, compressed air quality, network access, and who supplies the parts consumed during commissioning. Ask each bidder to state the throughput assumption behind any quoted cycle time, and whether that time includes part transfer, gripping, inspection, part release, or recovery from a fault.
Then force the commercial terms into the same shape. Ask for the validity period, the currency, whether duties and freight are included, the payment milestones and which acceptance event each is tied to, the lead time measured from which trigger, the warranty length on the arm separately from the integrator's own work, and the hourly rate for work outside scope. Two quotes carrying the same total can still differ by months of commercial exposure if one ties final payment to delivery and the other ties it to a signed acceptance test. Ask also who carries insurance and site liability during installation, since that line rarely appears in the quotation but changes the risk you accept when you sign.
Price the Whole Life, Not Just the Install
Add four recurring lines to every comparison, even where the supplier does not offer them: spare parts you will hold on site, the annual support or licence renewal if the controller software requires one, the cost of one engineer attending a programming course, and the cost of re-fixturing when the part family changes. Ask which spare parts the supplier recommends holding and which have lead times longer than your acceptable downtime. List the parts whose failure would stop the line, then check whether each is stocked locally or shipped from another region. For a collaborative arm used in a manual station, add the cost of the fixture changeover kit and the hours needed to requalify the process after any mechanical change, because those hours are paid by the operator's shift, not by the project budget.
Finally, write a short variance note for the two lowest bids: which buckets differ, by how much, and what technical question would close the gap. Ask the supplier to answer that question in writing before you shortlist. If the gap survives the answer, treat it as a real capability difference; if it disappears, the original quote was incomplete rather than cheaper, and the evaluation record should say exactly that.
Photo credits: the images in this article are licensed reference photographs of the relevant robot class, credited with author and licence in each caption; they are not photographs of the specific equipment discussed. Licence and author details are recorded with each image.