Today's remarks are governed by the safe harbor provisions of the 1995 Private Securities Litigation Reform Act.
For a discussion of the risks associated with VPG's operations, we encourage you to refer to our SEC filings, especially the Form 10-K for the year ended December 31, 2019, and our other recent SEC filings.
We have ended the quarter with a positive book-to-bill of 1.08 and grew our total orders 4.4% from the same quarter a year ago.
While the majority of VPG's facilities were able to continue operations due to the essential nature of our products, our two facilities in India and in China were more significantly impacted.
While this order has been extended to May 17, we received approval to resume partial operations on our India facility.
Financially, we have implemented a companywide salary freeze and have reduced our planned capital spending for 2020 by 30%.
For Foil Technology Products segment, first-quarter sales of $30.5 million grew 2.8% sequentially, reflecting growth in precision foil resistors and shrinkages in test and measurement and consumer markets, which offset weaker sales in the general industrial market.
Order for FTP in the first quarter grew from the fourth quarter of 2019 and included significant order for advanced sensors, which resulted in our book-to-bill of 1.25 as compared to 1.18.
First-quarter sales of Force Sensors of 14.7% -- $14.7 million declined 2.4% and from the fourth quarter of 2019, reflecting slower demand in the industrial weighing markets as well as modest impact from a temporary government-mandated shutdown of our China facility.
While a book-to-bill for Force Sensors in Q1 was 1.02, we expect our second quarter sales for these products to be impacted by the essential shutdown of our manufacturing facility in Chennai, India that I mentioned earlier.
Assuming the full reopening of this facility on May 17, we expect that our Force Sensors revenues in the second quarter to be reduced by approximately $5 million to $7 million, which is reflected in our guidance.
We also expect our operating profit to be impacted by approximately $3.5 million, reflecting the lower revenues, the required payments to employees during the shutdown period and of some partial operations and higher logistics costs.
Sales of Weighing and Control Systems in the first quarter of $22.5 million declined 7.9% sequentially.
Book-to-bill for WCS was 0.9 in the first quarter of 2020.
We believe we have ample liquidity with a net cash of $42 million on our balance sheet and a new revolving credit facility we put in place in March 2020 that not only gives us expanded borrowing capacity should we need it, but also offers us lower borrowing rates and more favorable terms.
Given the high degree of uncertainty in the macro environment, we are focused on what we can control, which are our key strategic initiatives, to both grow our business and to reduce our operating cost.
Referring to Page 7 of the slide deck.
In the first quarter of 2020, we achieved revenues of $67.7 million, operating income of $4.6 million or 6.9% of revenues, and net earnings per diluted share of $0.24.
On an adjusted basis, which excludes $515,000 of acquisition purchase accounting adjustments related to the DSI acquisition in November 2019 and $130,000 of restructuring costs, our adjusted operating income was $5.3 million or 7.8% of sales and our adjusted net earnings per diluted share was $0.29.
Our first-quarter 2020 revenue declined 2.1%, compared to 69.1% -- $69.1 million in fourth quarter and were down 11.5% as compared to $76.5 million in the first quarter a year ago, which was also a historical high quarter for VPG.
Foreign exchange negatively affected revenues by $600,000 for the first quarter of 2020 compared to a year ago and had no impact as compared to the Q4 of 2019.
Our gross margin in the first quarter was 37%.
Our gross margin on an adjusted basis was 37.8%, which improved from 36.8% in the fourth quarter of 2019.
Our operating margin was 6.9% for the first quarter of 2020.
Excluding the above-mentioned purchase accounting adjustments and restructuring charges, our first-quarter adjusted operating margin was 7.8%, which increased from 7.5% we reported in the fourth quarter of 2019.
Selling, general and administrative expenses for the first-quarter 2020 were $20.3 million or 30% of revenues.
This compares to $20.4 million or 26.7% for the first quarter of last year and $20.2 million or 29.2% in the fourth quarter of 2019.
The adjusted net earnings for the first quarter of 2020 were $3.9 million or $0.29 per diluted share, improved from $3.7 million or $0.27 per diluted share in the fourth quarter of 2019.
The impact of foreign exchange rates for the first quarter of 2020 was positive compared to the first quarter of 2019 by approximately $400,000 or $0.03 per diluted share.
We generated adjusted free cash flow of $3 million for the first quarter of 2020 as compared to $4.8 million for the first quarter in 2019.
The GAAP tax rate in the first quarter was 32.3%.
We are assuming an operational tax rate in the range of 27% to 29% for 2020 planning purposes.
We ended the first quarter with $82.7 million of cash and cash equivalents and total long-term debt of $40.6 million.
Turning to our outlook, given the expected impacts resulting from the COVID-19 pandemic, we now currently expect net revenues in the range of $56 million to $62 million for the second quarter of 2020, which assumes constant first-quarter 2020 exchange rates.

Summary:
For a discussion of the risks associated with VPG's operations, we encourage you to refer to our SEC filings, especially the Form 10-K for the year ended December 31, 2019, and our other recent SEC filings.
While the majority of VPG's facilities were able to continue operations due to the essential nature of our products, our two facilities in India and in China were more significantly impacted.
While this order has been extended to May 17, we received approval to resume partial operations on our India facility.
Assuming the full reopening of this facility on May 17, we expect that our Force Sensors revenues in the second quarter to be reduced by approximately $5 million to $7 million, which is reflected in our guidance.
Given the high degree of uncertainty in the macro environment, we are focused on what we can control, which are our key strategic initiatives, to both grow our business and to reduce our operating cost.
In the first quarter of 2020, we achieved revenues of $67.7 million, operating income of $4.6 million or 6.9% of revenues, and net earnings per diluted share of $0.24.
On an adjusted basis, which excludes $515,000 of acquisition purchase accounting adjustments related to the DSI acquisition in November 2019 and $130,000 of restructuring costs, our adjusted operating income was $5.3 million or 7.8% of sales and our adjusted net earnings per diluted share was $0.29.
Our first-quarter 2020 revenue declined 2.1%, compared to 69.1% -- $69.1 million in fourth quarter and were down 11.5% as compared to $76.5 million in the first quarter a year ago, which was also a historical high quarter for VPG.
The adjusted net earnings for the first quarter of 2020 were $3.9 million or $0.29 per diluted share, improved from $3.7 million or $0.27 per diluted share in the fourth quarter of 2019.
Turning to our outlook, given the expected impacts resulting from the COVID-19 pandemic, we now currently expect net revenues in the range of $56 million to $62 million for the second quarter of 2020, which assumes constant first-quarter 2020 exchange rates.